I try to gather here all the rules that I've found that will trigger anything between raised eyebrow and epic RAW-lawyering.
If you find other rules which surprised you, please add below.
Thanks.
EDIT: Sensible issues highlighted. I summarized the tough rules issues here.


Army wide rules:

- Hatred (HE). Is it all units from HE AB? Is it "ethnic" high elves? Debated here: Hatred: High Elves

- ASF: Vs other ASF troops, all attacks are simultaneous, ignore the I.
BRB p.66: ASL+ASF do cancel out, model strikes at I.
In case an ASF/ASL model fights an ASF model, as the ASL does cancel model's ASF, it is not a case of ASF vs ASF.

- Eternal hatred: Army wide??? In fact, it is not only for BG, but also 3 special characters: Malekith, Malus, Kouran.

- RHB shoot at 12” but now have penalty for long range.
Thanks to quick to fire, you can move (not double-move) and shoot with no penalty, and S&S at any distance.

- SDC is improved in melee, provide scaly skin 5+.
Dreadlords & Masters can get it, Beastmaster & Fleetmaster have it built-in for 4+ total AS.


Magic:

Hekarti’s blessings, +1 to cast Dark Lore: not available to warlocks.

Attribute when rolling double and triple, additional hits do not cumulate. E.g. 2/2/3/3/3 gives only 3D6 hits.

PoD: if it wounds, ward saves are still allowed.

Spell #5 is direct damage, i.e. centre of template must be in sorceress front arc, and template must not touch any unit in combat or allied unit – but may aim empty location. Now, after deviation, it is no longer restricted, so it may move out of range, out of LOS, on combat, on allies, it will suck out life all the same.

Spell #6 Vortex needs to be set in front arc, too. It deviates less than other vortexes.


Magic objects:

Chillblade autowounds. It does not specify autohit.

Cloak of Twillight won't protect you from miscast damage (it's not a spell) but it will protect you from Power of Darkness wound and badly scattering Black Horror.

Ring of Hotek affects only enemy wizards. Either the caster or the target need to be within 6”.
The English edition requires some thorough reading, but the French edition is crystal clear.
Note: It says attempts to cast. So even a spell that does not go off can force a miscast.

Gem of Spite seems only useful for a Death Mage on Pegasus using default spell.

The rebound of the Black Amulet only works in challenges (but isn't much cheaper). So if you get mobbed by some goblins, don't expect to take any extra down with you...
- Please do not imagine what could happen with two opposing DE armies, each with such item. No, dooon't... too late, you're trapped in perpetual rebouncing "Wound tennis".

Tome of Furion: You select one spell and randomize the other spells. Note that if you randomize the very spell that you happened to have chosen, RAW allow you to keep it twice, despite common sense understanding. Note that it does not go as far as allowing you to switch a spell randomized twice for the selected one. See Duplicating spells via Tome of Furion for more.


Lords & heroes.

Note that all special characters became cheaper except Malus who became lord and Kouran & Tullaris who became heroes.

Malekith still may use CO or COC. His general's Ld bubble is 6" wider than other generals, which is excellent with all these Ld6 or Ld2 monsters.
Note that he gets +1PD or DD. His dragon has better stats than regular ones.

Morathi still must ride her Pegasus, which has better stats that regular ones. She no longer may get magic objects.
Having guaranteed access to Death signature is huge for a mobile Ld10 caster.
Note that Sulephet does not benefit from the model's Murderous Prowess: it specifically excludes mounts.

Hellebron has effectively 7+D3 attacks, S10. She may ride manti or COB or nothing.

Malus has been promoted lord. Spite has been upgraded too, instead of removing stupidity as previously, he forces stupid tests to autopass => they remain ItP! However, Malus needs to be with COK to become ItP thanks to their stupidity. Other rules have been marginally changed.

Dreadlord changes are small.

Beastmaster is better than dreadlord on Manti thanks to his special rule, but gets less equipment.
On a S-runner, with his BS7, he needs 0+ to hit so may afford move & shoot and long distance for no penalty.
To be compared to scroungerunner's natural BS4.

Fleetmaster , one may wonder why take him rather than a dreadlord, except for fluff. Similar cost, lesser stats, much lesser equipment. Cannot even use our Black Amulet in challenges.

Supreme sorceress got 40 pts cheaper.

Shadowblade has improved dramatically and has become cheaper, with 5++ and all gimmicks. But no longer deployment inside enemy.

Lokhir improved armour save to 2+, contrary to fleetmasters. He may hit a character not in base contact but in same melee (watch you, sorcerers). Cheaper, too.

Tullaris gives frenzy to own unit, even if not Execs.

Kouran upgrades only BG. His armour hits back "immediately", i.e. the hit back is resolved at same I as the incoming hit.

Sorceresses cost 20pts less and chose among 9 Lores but lost use of unlimited PD.

Death Hag's witchbrew: if a DH gives witchbrew to a non-frenzied unit, herself does not get any benefit. Double-frenzy is a mass distraction only.
Discussion here
On the other hand, RAW seems to bestow Inextinguishable Frenzy for Hellebron, Tullaris and DH, even if they lost a combat, and Perpetual Frenzy for any unit they touch, till they lose combat, even after they have left the unit.

Assassin deployment remains as before.
Assassins have lost scout rule. Models that are neither represented through an actual model nor through a marker on the table do not effect the game in any way. So as Long as you do not deploy the assassin unhidden, he is not deployed at all, he is not on the table and he cannot steal scouting rules from Scouts. But when deployed inside a scouting unit, the 'sass may well charge in turn 1!
Please note that this has also negative effects on DE assassins, as they cannot use Magic items as Long as they are not part of the game. This is especialy nasty if he is equipped with a potion of strengh. Those potions must be used at the beginning of a round, so if you reveal the assassin at the beginning of a Close combat, he must not use his potion.
They are ItP Ld8, which is little use except when alone, but if alone, they are as good as dead anyway.
Assassin has thrown weapon: 6”, quick to fire, S as thrower. As sass have BS9, needs to roll more than -2 on D6, so +4 modifiers won’t change anything.
Poisons: no longer replace the regular poisons, it stacks. Poisons work with thrown weapons & RHB (12” and 2 shots); but only manbane is useful at distance, making S4 shots; KB, however, is NOT effective at distance (BRB p.72); and Ld reduction is hard to use against a character you cannot shoot inside a unit.
Also, a strange combo found by Gerner, manbane does effect wounds made by Ruby Ring of Ruin. They get +1 to wound.
Sass may take magic objects. Note that magic armours are available! See Hashishin loadouts for a few samples. But remember, a magic weapon does not get any poison.
EDIT: Note that there is no longer any limitation in how many assassins may hide in a single unit.


Mounts:

DS got fast cav for all characters! Vanguarding characters? Nice! Cost slightly increased to reflect that.
Lord/hero on dark steed, heavy armour, sea dragon cloak, shield = 1+, still fast cav.

Dragon has hatred (HE), suprisingly, but not other DE racial traits.
Its breath no longer triggers a Ld test, but causes -1 BS and WS.

Manticores did not change at all.
Manti gets 50pts cheaper and can buy improvements, 4+ or +D3A. Could get D3A more from Beastmaster, total 4+2D3+ possible frenzy. Still KB.

Only COC became 30 pts more expensive (as mount, while as unit, it went only +15 pts) - must be because of mounts getting 2A.

COB is a chariot, therefore D6+1 impact and swiftstride. Also, dangerous terrain becomes very dangerous.
- Despite being a chariot, it may march and join units as a character (only 1 chariot per unit, must be in unit’s front centre) (may even join fast cav, COK, medusa, other characters, but not RBT, COC, monsters or flyers - consequences are debated here). Models behind it are in the 6th rank and do not get supporting attacks. It is not considered as a character in a unit, therefore no Look out, Ma’am (and it is a large target). See herefore detail.
- The COB itself has 6+/4++, the DH on it has 5++, the unit surrounding it has 6++ (or 5++ if WE). MR(1). 5 wounds. Don’t forget it causes terror. The 2 WE are exactly like regular WE, except that being mounted, they do not benefit from AHW (and neither the DH and Hellebron when on a COB), see BRB p.91.
- The DH is a character on a chariot, no more no less. Shooting randomizes, 5-6 on D6 goes to DH. Templates touch both. If chariot is destroyed, the DH remains. If the DH is killed, the COB remains.
- Strength of Khaine: RAW speaking, COB makes reroll to wound even for magic spells and for shooting, the only requirement is to have murderous prowess - but RBT themselves do not have it, only their servants. Note that mountssuch as pegasus, CO and DS would get the COB's reroll, too. Note that it fits not the fluff, so chances are high that this rule has been overviewed. Many players will play SoK only in melee and not for mounts, despite RAW clearly more relaxed.

Note that Life #5 Regrowth specifically does not work on characters nor on mounts (last-but-two sentence). But Lifebloom Lore attribude works.


Core units:

Corsairs definitively must take a 2pts option, increasing their cost to 11pts effectively. Including the reaver, even if he buys the pair of RHB.

DR: I see no reason for not taking shields.

WE: the only core troop to get 50pts standards (only 1 unit).

DR: no magic standard. DR champ lost its additional attack.


Special units:

Harpies: no special rule except fly. May panic other units now. Much more expensive.

Shades & harpies: only infantry to be 5+.

Shades: no magic standard. Gained FC but the champ lost its additional attack.

COK, BG: only champs able to take a magic weapon (not object).

Execs gained Ld9.

Scrunner is a chariot, the only one with only D6 impact. Crewmember have 2 A each and spears.
Harpoon: when dragging a monster, it does not specify that facing of target is modified, so it must not.
1 RXB each, at BS4. Nothing prevents to use both the bolt thrower and the two RXB, but must be on same target. RAW, Stand & shoot is allowed.
Beware, the harpoon has not the rule "ignore armour saves", therefore armour saves are authorized.

RBT shoots as before, except its 6-shots have AP rather than -2 to AS, and it is NOT multiple shots, RAW it doesn't suffer the -1 to shoot penalty.
They do have the rule murderous prowess, therefore RAW speaking, COB makes reroll to wound thanks to Strength of K.

Hydra’s regen changed dramatically. No handlers in the rules. Ld dropped to 6 when lost the handlers.
It does not reroll anything, no hatred, no murderous prowess. Still 4+, still terror.
Hydra may upgrade either a breath attack or a shooting attack.
Shooting is 8”, S & shot numbers = remaining wounds, flaming. It has BS4, moving, multishots and range penalties do apply, stand & shoot allowed.


Rare units.

Warlocks do have poison (not their steeds), and 2 attacks each (3 for champ). No muso, no pennant.
The whole unit is a lvl2, casting originates from any one model. Miscasts (D3 wounds) allow the 4++ (but magic resistance would not help any further against miscasts). Don't forget that the respective lore attributes are applicable (either Death of Dark).
A champion is allowed, but has no use except +1 attack and may challenge.
Warlocks are must-haves in Storm of Magic games. See why here.

Kharibdyss don’t have handlers rules and are not sea creatures despite fluff. Poisoned attacks, by the way, in case it might be useful at S7…
It does not reroll anything, no hatred, no murderous prowess... but it makes opponents reroll Ld tests. Note that a rerolled dice cannot be re-rerolled (BRB p.7) in case the opponent's BSB is in range.
Feast of Bones will rarely be seen, Kharibdyss must first hit with all attacks, and chances are low. See Golan's stats here.
There's a discussion about whether R&F can be targeted for a nice bone feast overkill. See Kharibdyss' Feast of Bones against units.

Shrine is a chariot, therefore D6 +1impact and swiftstride. Also, dangerous terrain becomes very dangerous.
Despite being a chariot, it may march, and it may join units like a character (only 1 chariot per unit, must be in unit’s front centre) (may even join shades, fast cav, COK, medusa, other characters, but not RBT, COC, monsters or flyers). It is not a character, therefore no Look out, Ma’am (and it is a large target). See herefore detail. Models behind it are in the 6th rank and do not get supporting attacks.
The shrine has 6+, no ward save. Don’t forget it causes terror. The 2 crew are not WE, only 1 A each with lance (+1S on the charge), no poison, no frenzy.
Shrine Ld boost is capped at Ld10, see BRB p.3.
Watch out: Shrine Ld boost & hex is for models, not for units. If there is a single model in the enemy unit outside of 6", the -LD effect does not apply (since you can use the LD of that model).
The medusa is part of the crew, it cannot be singled out. The medusa has all DE racial rules (ASF…).

Medusa and shrine are different units, so it is possible to get 2 lone medusas in addition to 2 shrines.
Lone medusa M5 T4 W3 Ld2, frenzy, no armour, fear, may be joined by characters.
Shrine medusa M7 T6 W5 Ld8+1, 6+, terror, large, may join units, impact, crew, larger footprint for Gaze’s KB, no frenzy.
Stare is shooting at range 12", S4, KB and multiple shots (4). When rolling to wound, substitute the target's T with it's I value. No armour save allowed. It is a shooting attack that happens to be magical (so long range, multiple shots, move & shoot penalties apply, you cannot double-move and shoot but you can Stand & shoot). Strange as it seems, even a shooting attack which consists merely as looking at peole may not be quick to fire, and get a penalty for moving...

Note about Medusa's Ld2, it is not the end of the world:
- as long as it is frenzied, it is ItP
- it causes fear so fear does not affect her.

nice breakdown of everything on one page
except CoC only went up 15 not 30
and cold ones got 2 attacks

COC as mounts went up 30pts. But you're right, I've edited.

The rebound of the Black Amulet only works in challenges (but isn't much cheaper). So if you get mobbed by some goblins, don't expect to take any extra down with you...

Added, with complement:
- Please do not imagine what could happen with two opposing DE armies, each with such item. No, dooon't... too late, you're trapped in perpetual move.

Would the Cloak of Twillight protect you from miscasts?
It says "against Wounds caused by shooting attacks and spells".
If I remember correct the miscast damage isn't considered spell, you can't use MR against it per example.

It won't protect you from miscast damage (it's not a spell) but it will protect you from Power of Darkness wound and badly scattering Black Horror.

COB or RBT? MoP clearly states the reroll only counts in CC attacks, so you don't get it on ranged.

Another note: the multiple shots is considered an alternative "rule". Not "multiple shots". As such, RAW it doesn't suffer the -1 to shoot penalty from using 6 shots.
What's the HE take on this?

I don´t think the Killing Blow poison works on ranged attacks. It doesn´t mention killing blow with all his attacks, it specifically gives the model KB, and KB only works for close combat attacks unless otherwise specified.

RAW, RBT and sorceresses have MP as a model. RAW, when those models fail to wound in magic or shooting, the COB makes them reroll.
RAI, it is highly likely that the COB's reroll was intended in CC only, and the first FAQ will sure fix that. But that is not what RAW state.
Meanwhile, I feel that Druchii.net can only acknowledge what RAW says, but should recommend not to use it and use RAI instead.



Oops! My mistake. Will edit.


Other points taken.

In addition, as Scyloc has discovered:
Tome of Furion: You select one spell and randomize the other spells. Note that if you randomize the very spell that you happened to have chosen, RAW allow you to keep it twice. Note that it does not go as far as allowing you to switch a spell randomized twice for the selected one. See Duplicating spells via Tome of Furion for more.

my thought on the CoB and the re-rolling of wounds with shooting is no it doesn't.
the reason for this is because RXB and RBT use their own stats and special rules when working out damage. the only stat that is used when firing these weapons is the users BS.
after all if the CoB could be used for their re-rolls to wound then mindrazor would also work with shooting (which it doesn't)

That's a bad analogy because mindrazor specifies close combat attacks only.

I agree. You can word lawyer this rule and say it applies to ranged as well but I believe that it was clearly meant to be for CC. I've already discussed it with my group and we will play it for CC only until a FAQ is released that says otherwise.

I don't think it's "rules lawyering". As written, the rule clearly says "all" to wound rolls. There is no twisting or strained interpretations required to read the word "all" to mean "all".

Further, we don't have any basis to assume the intent was to limit the effect to close combat. Some people point to the fact that the effect is limited to models with the Murderous Prowess rule and argue that since that rule only applies to close combat, the Strength of Khaine rule must have been intended to be limited in the same way. The strongest indicator of intent is always the express language, and here it is unambiguous that the effectapplies to "all" rolls to wound. Moreover, the limitation to models with Murderous Prowess may simply be a quick way to indicate that only actual Dark Elves (rather than monsters, harpies, etc.) benefit from the effect without having to list all the things that don't benefit.

I agree, the rule as written is actually very clear: All models that happen to have the MP rule (all elves) get to re-roll all to-wound rolls. I would therefore definitely play it this way.

If GW wants to change this they have to do an errata (changing the rule) rather than a FAQ (aiding the interpretation of an unclear rule)

Something I thought about was the possibility to give an assassin Manbane + Ruby Ring of Ruin since it stacks.
Unfortunately he doesn't have the snipe rule.
But it could be a "sure" way to remove reg saves or put a few extra wounds.
Still looking for better assassin builds.

There is no broken combo here. Unless otherwise specified, rules that affect the model doesn´t affect its spellcasting capabilities. Hatred doesn´t apply to spells, nor does reroll failed rolls to wound, KB or Flaming Attacks from the Flaming Banner.

It says ALL to wound. I know it isn't broken - but anything to help this poor guy (the Assassin that is).

Unexpected discovery: if a DH gives witchbrew to a non-frenzied unit, herself does not get any benefit.
Discussion here

I don´t buy it, it´s a too liberal interpretation of the rule. I haven´t heard of any rule, anywhere, that allows you to reroll failed rolls to wound with spells. In all instances that I´m aware of special rules does not affect your spellcasting.

"never heard" is not an argument. Did you ever heard about a chariot joining units?
Edit:
Gerner has a valid point, rulewise. Ruby ring would indeed get +1 to wound thanks to manbane. With a similar logic, Empire witch hunters get KB with the same ring.

The chariot can join a unit because it is permitted in its own rules. Reroll to wound with spells is not expressly allowed in the CoB rule. It is two completely different situations. Chariots joining units is something new and require a rule that specifically allow this, so they wrote it in. Reroll failed to-wound rolls with magic is something completely new too, if this was what they wanted the CoB to do then they probably would have specified it, like they do most other times. I understand that there is an argument for a reroll for shooting and spells, but not everyone would agree with that interpretation. There is an argument based on RAI, precendence and FAQ from similar situations to read the rule other way around. I think this is one of the situations where it´s best to take it up with your opponent and/or the judges of a tournament first, avoids nasty arguments and surprises all around.

How can you express it more expressly than *all* rolls to wound?

"All" is pretty inclusive.

Precedence from other rules. Spells are rarely if ever affected by special rules, and if so the rule clearly specify what effect it has on spellcasting. Killing Blow, Hatred, Flaming Attacks, none of them interact with the spellcasting, even when the spell does close combat attacks, FAQ:ed in our last book. If they could reroll wound rolls wth spells then it would be a completely new and unusual buff to wizards and they would most likely have clarified, not because "all" might be unclear but because few would even think of rerolling wounds for spells if it wasn´t pointed it out in the rule. Even if we ignore that, I can argue that wizards cast spells, but the spells are separate events. The wizard can reroll failed to-wound rolls, the fireball can´t.

Of course it´s not an iron-clad reasoning, but I´m not the one applying poison to my fireballs

It would not be unprecedented for an effect to allow rerolls of all to-wound rolls. In the previous version of the Empire book, the Hammer of Sigmar prayer allowed rerolls to wound and it was not limited to close combat. It was a very common tactic to use the prayer on a wizard's unit in order to get rerolls to wound with magic missiles. Although Hammer of Sigmar is now limited to close combat, there was no big controversy when it applied to everything. Nor should there be a controversy with the Cauldron now. Just play it as it's written--reroll all failed to-wound rolls. Powerful? Yes. But that's no reason to ignore the plain meaning of the rules. If that's a valid argument, that means I get to completely rewrite the Skullcannon and Ironblaster since I think they are overpowered. After all, there was no prior precedent for chariot-mounted cannon that can move and shoot, so there is no way GW could have intended for them to be able to do that.