Reincarnation with certainty can work on world bosses. It does not always succeed, as mentioned by many Chronomancer players who have tried and failed. It’s not only possible to resurrect the boss for additional loot and money (the EXP is usually negligible) but it’s possible to do it in multiple instances in a single encounter. We’ve seen Necroventer in the Legwyn Family Residence revived twice in a single fight, for three cubes of loot.
Death Sentence makes no sense to work on world bosses that don’t have the ability to dispel themselves. World bosses have millions of HP, as high as 200’000’000, and having a skill that can instantly kill one that’d otherwise take a very long time and effort to defeat would be fairly nonsensical.
As Death Sentence is a level one debuff with a long cooldown, with a duration that really doesn’t make much sense considering you can probably kill the targets with regular skills in half the time, I’m going to say a resounding and generally accepted opinion among high level Cleric players that Death Sentence is a very bad skill to invest in, in its current form.