Regeneration

[Littlenog]

Why type of attack damages cancel out regeneration.

It seems life stealing or create undead attacks and turn to stone attack do.

Is there a list of what other attacks stop regeneration?

[Nelphine]

Cracks call does as well. I'm sure there's another one but I can't think of it offhand.

Note, these attacks also prevent raise dead. (And I so love me some raise dead).

Confusion and possession also stop them. Though that's not strictly damage.

[Juffos]

Disintegration and Wave of Despair. I'm not sure if Wave is meant to be unrecoverable.

[Seravy]

Exorcise, Holy Word, Great Unsummoning, Banish, Creature Binding as well. I think that's all. Yes, wave is intended.

[Littlenog]

Was doing some blood lusting trolls which was really fun and noticed they were not all coming back

Only mistake I made was not getting some better races to SIM city once I had map control.

[teelaurila]

This seems to explain pretty well the create undead damage and irreversible damage:

http://masterofmagic.wikia.com/wiki/Damage_Points

It seems the notable difference is that regeneration can heal create undead damage in combat, but neither regen nor raise dead will bring back a unit killed by create undead damage.

I suppose in CoM death immunity makes all create undead damage normal? So bloodlust trolls should come back if killed by ghouls, but normal trolls not. (But it seems you're playing the game wrong if your undead trolls get killed by ghouls or zombies.) Does magic immunity make create undead damage normal? (Challenge to get an undead sky drake!)

Pretty much everything in the irreversible damage category is a major threat to the trolls though.

Speaking of which, is it clear how it gets decided whether a unit is raised as undead? My gut feeling from playing is that it's not if <50% of damage is not create damage, and if >50% it depends on the amount. I.e. I can't seem to get consistent raises unless I kill the unit with nothing but create damage.

[Seravy]

It's 50% or more creature undead damage, but "excess" damage dealt over the unit's actual health also counts.

[Nelphine]

As an example: creature has 10 hit points. You do 7 damage with your ghouls (more than 50%, good right?) Then you hit it with your super Torin of doom for 18 damage.

Even though the creature only had 3 HP left, 18 > 7, so the create undead damage is less than half.

(This is why death knights and demon lords virtually can't create undead. Their normal damage is too high. Even wraiths can have problems.)

AI can get undead sky drakes