Power Word Kill is a 9th level spell that "compel[s] a creature to die" as long as it has less than 100 hit points.
If this is cast on a druid in wild-shape form with less than 100 HP, does the druid die or does he only revert to his normal state? Is the "creature" the druid himself? Is wild-shape a creature on top of the druid, or is he always the same creature?
I realize that a druid is only knocked out of wild-shape if he hits 0 hit points or is knocked unconscious, so my personal take is that he would simply just die due to the wording of the spell, but I was curious if I was perhaps missing something.
Best Answer
By RAW, the Druid dies.
Wild Shape protects you from a few specific things:
When you revert to your normal form, you revert to the number of hit points you had before you transformed (and then take overflow damage).
If you revert and have hitpoints remaining in caster form, you don't fall unconscious as a result of being reduced to 0 hit points.
Power Word Kill bypasses both of these restrictions by killing the Druid rather than dealing damage or reducing its hit points to zero. Returning the Druid to life (or preventing its death) is not one of the things that Wild Shape does.
This is basically the same argument as the one for massive damage, except that there's definitely no sequencing of events. The Druid dies, and Wild Shape doesn't protect you from dying. Game over.
House ruling options are slim here. Killing a druid for using a utility form is harsh. On the other hand, relegating a 9th level spell to "knock a druid out of wildshape once" is also pretty rough.
Just the Wild Shape's. Wild Shape says:
Like most of your other stats, your old hit point total "goes away" while you're in beast form. Your hit points are the beast's hit points.
With that said, adding beast hit points to caster hit points, or using the Druid's base hit points for spells such as Power Word Kill may be a useful house rule.
This ruling is confirmed in the Sage Advice Compendium, the source of official rulings from WotC:
Jeremy Crawford
This has been confirmed by Jeremy Crawford: