Another Beseechment of Strange Powers to fulfill Particular Desires, laced with Hidden Consequences, while I'm thinking of it.
The party had acquired the services of an efreet, purchased 'second hand' from an arab foreigner who had acquired it himself (or so he said) as a reward from a caliph for rescuing the caliph's daughter.
It was a quiet, small, iron flask with a chained stopper and impressive looking arabic written in cribbed writing, and they got it translated long before they ever tried to use it: basically, "big mojo, powerful efreet, but get a lawyer"

.
They dragged that thing around for probably a year before finally deciding they needed it (to defeat a necromancer), and when they did finally pull it out, they forgot the lawyer.
The conversation ran roughly thus:
"Thank you, O my young lords, for allowing me to discharge my obligation to he with whom I contracted, may his loins find no ease from a thousand diseases."
"So, uh, what kinds of wishes can you grant?"
"Wishes, O My Masters? I grant but one! As for it, anything within my power is yours to command, and my power extends over the earth and heavens alike. Declare an enemy, and he shall burn in a thousand fiery hells. Declare an object, no matter where, and I shall acquire it for you between heartbeats. Declare ambition, and I shall head an invincible legion for a year and a day to establish your place."
"So, for example, and this isn't necessarily what we are wishing for yet, if we asked you to slay the necromancer in that tower over there, you could do that?"
The efreet takes a long, careful look at the tower, apparently gauging the effort.
"O My Masters, know this. If you wished me to, I would burn the very stones of that tower to fine ash. I would rain fiery meteors from the sky upon the ash, leaving naught but a craterous ruin. The very earth would weep tears of fire, and nothing that was in or around the tower would survive your wrath."
"So... what does 'around the tower' mean?"
"O My Masters, I mean only the small area of land immediately surrounding it. Ah, but I see you want specifics, so perhaps 100 yards would be good."
The PCs made sure they were more than 100 yards away, then...
"Okay, do that!"
The efreet flexes his mighty hands. The very stones of the tower burn. Then meteors fall from heaven. Then magma bubbles up from beneath, and consumes the land itself. One lone fire elemental bound to the necromancer's forge survives, and the efreet makes a great show of squashing it between his mighty toes. Nothing beyond the 100 yard radius is touched.
Everyone is
very impressed, and the efreet disappears, leaving only the ancient flask.
Unfortunately, the necromancer wasn't in the tower at the time. And if you look carefully, the efreet never actually answered their second question (after all, they said they weren't necessarily wishing for that).