ToME: the Tales of Maj'Eyal

As the question asks. Under what circumstances (classes, races, builds...) do you corrupt the Sandworm Queen's Heart for Vile Life, instead of eating it right away (for Harmony or just the points)?

I think that Undead can only eat the Corrupted Heart, so that's one point in its favour.

Say, you really want the anti heal talents in those lines for some reason. And you are a vim user so harmony is completely out, then you go for Vile Life.

If you cannot really spare the points to learn it or use equi talents and don't want Harmony either, just eat the heart asap.

When you're undead and want Draconic Will. If you're undead, eating the regular heart won't give you drake_touched but eating the corrupted heart will, so it's required in order to get Draconic Will.

As far as the actual Vile Life category, Healing Inversion and Elemental Discord are ruined for most classes by requiring you to beat the target's save with your spellpower (Healing Nexus has no such check). Yes, even Elemental Discord's slow and burn have to beat saves, giving them the dubious distinctions of being the only direct slow and burn in the game that check saves. Healing Inversion also uses the pre-healmod healing value so it's worse than it looks in that regard too.

Blood Splash on the other hand is actually good for the on-crit effect, but it's not like it's worth a category point on its own, and classes with enough spellpower to use the other talents are almost always classes that have lots of other things they want to unlock more (pleeeease remove tinkers and Celestial/Light from escorts). Possibly it's worth unlocking on characters that are already celestials sometimes, undead anorithil doesn't really have a better place for that last category point.

Vile Transplant is bad on the surface, and it requires beating spell save with spellpower to transfer each effect even if you transfer to an allied creature. On the other hand, you can probably break something with it.

Of course the biggest problem with corrupting the heart is that eating the heart right away gives you a benefit during the part of the game where it actually matters. By the time you can corrupt the heart safely you're nearing level 30 and have pretty much already won.

I'd say waiting for so long to corrupt it (or being mad enough to brave Mark of the Spellblaze early) should reward you with the tree already learnt or trigger a quest that leads to doing so, but it doesn't. If it wasn't for the cat point requirement I'd probably see use for it on something that can reduce the relevant saves. Like Demonologist's Shattered Mind.