Thats what ended up being used yes, but the meme pretty obviously is referring to someone being scared they're going to be Power Word: Killed

Crucio!

When they put you against someone using it in Baldur's gate 3 the make it a three turn ritual, so you just need to break the caster's focus and you get a few goes at it

Makes sense. One of those "it's easier to add than subtract" things. I probably won't do that, but if it works for you, then that's good.

I used to ask people to tell me if they need healing, but I found it easier to just keep track of it all myself so that I can plan when to switch roles from buff to heal.

Combat encounters usually have me bringing out a calculator and a sheet of paper where everyone's hp is being tracked.

There are ways. You could, for example, set up a bbeg where that's his whole deal. The townsfolk are scared of this guy because he has the supernatural power to just kill you, straight-up. Maybe the questline leading up to their encounter involves the players finding defenses or counters or sabotaging his supply of spell components or whatever, such that, if they DO get power-word-killed, it's because they had ample opportunities to not, and failed to take them.

It's definitely one of those things that you shouldn't just throw out there. Gotta plan for it

Can make for some epic moments depending on the party and setting and fight etc. My character in the first stage of the final fight of the campaign got power word killed after getting the BBEGs lair action enabling staff away from him, because taking the staff hurt him enough to put him under 100. Incredible narrative moment, didn't expect the disarm to work and he passed it off with his dying breath. Got revived in a later stage once reinforcements started showing up

Yeah, of course you need to know to resolve the effect

from what i understood, the dm asked to know if the spell would have effect, not if the creature was going to use it or not

Because the DM needs to know if the spell succeeds before they can narrate anything.

I also didn't downvote, but maybe you would want to convey the information to your players that creatures here can use that spell without outright killing a PC in the first battle? Like "you guys should really watch your health points in this area" type of thing

I didn't down-voted. However, I would somehow disagree. Knowing how badly injured are the PC allows to adapt the tactic, in both direction. Yes the warrior is a tank who can take tons of hit (is there really games where PC have 100 HP ? that much ? ) and you have that social character who can't do much in combat, who is usually unconscious at the end of the first-round. So knowing how much HP do the PC have helps managing the right level of power against them and avoid stupid character death.