Situational spells that are super good for certain encounters?

Hey gang,

I'm curious about y'alls own usage for spells that aren't normally useful in general gameplay, but come in clutch in particular encounters.

Example: Calm Emotions

I don't find this spell useful most of the time, but I know of two encounters where it comes in clutch

Harpies on the beach. Calm Emotions makes your group totally immune to being lured, removing the biggest danger point of the fight.

And

Meenlocks below last light inn. Calm Emotions also makes your group immune to meenlock fear, turning an encounter which is usually a pain in the ass into one that goes smoothly.

Or even generally useful spells that become suddenly very powerful in specific encounters. For example

Bone Chill on Myrkul's Avatar, nullifying the main mechanic of the fight.

Also stuff like Knock to skip the trials in Shar's temple is good and cool. Does that even still work?

I really like spells that have these very small niches where they come in clutch and I'd be interested to hear what more I've missed.

Edit: Please everyone. Spirit Guardians is not a situational spell. Fireball is not a situational spell. Command is not a situational spell. I'm really looking for stuff that's usually not good here.