Finding if an NPC is alive

Sorry to clog the tubes with retarded questions but I have no idea how to tell if an NPC is alive or not, because NPC:Health() and NPC:Alive() don’t work. Is there something that I missed that’s incredibly obvious? NPC:IsValid() works but it takes about 2 seconds after you’ve killed the entity for it to be removed and not a valid entity.

NPC.Health works fine serverside, so I assume you’re trying to check it clientside.
Well, afaik there’s no way to do that aside from using NPC.IsValid, but as you said already, that still returns true (On vanilla NPCs) after their death until about 2 seconds have passed.
The only other way I can think of right now, is to create a serverside hook to EntityTakeDamage, check whether the damaged entity is a NPC and whether the new health is below 0, and then inform the client about it.

Yeah, I am trying to do it clientside. I have seen videos of different scripts (one being an aimbot) that flipped through all the npc’s in less than a second, only going to the next one when the current one is dead. If they did it with an aimbot it can probably done somewhere else, but I have no idea how D: