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.