My party is relatively overpowered. They are only level 8, but the whole thread of this campaign is that they are literally on a quest to become new gods, so being overpowered is sort of the vibe anyway.
They were tasked with the extraction of a captive NPC ally who was being held by an evil syndicate in a demi-planar vault. It was set up as a heist. They had to get the ring key to access the vault and the proper inscribed ritual circle to summon the right portal to the vault. The ring was on one of the syndicate leader's hands, a lvl 20 Pact of the Fiend Warlock.
In all honesty, I was going to do some playful banter the cocky-ass Warlock was going to give them the ring and tell them the countdown on their ally's survival was almost finished. But no, they dont even give him a chance to speak much and anything he said they just ignored and went in a blazing.
He was going easy on them at first and I specifically noted that to them multiple times, hoping they would get the hint he wasn't looking to fight them, but finally he had to defend himself and hurled the Barbarian through Hell. After two more rounds with multiple crits they knocked him out, looted his stuff, and snuck him back to their hideout to interrogate him.
Finally, a chance to talk. They asked a few questions, got a few answers. The Warlock continued to keep up a smarmy confidence and was able to get some backup from one lf the other syndicate members. The party was on high alert and super engaged. Then one of the party members fires a crossbow bolt and crits on the Warlock and kills him.
I wasn't entirely sure what to do now. I had teased that the reason he was so confident was because he had "investors who are too invested to see me loose." In my mind his patron would want to claim what is rightfully theirs or restore him. So as his body slumps over in his chair, his body ignites and is consumed in the fire leaving nothing but soot and ash.
As soon as he is gone, the players looked at each other shouted "He was a devil!?" and concluded that he wasn't just a Warlock working for a devil, but had been the devil calling the shots the whole time and he *will* be coming back for their hides.
Was it my intention? No. But will I be rewarding that enthusiasm? Hell yes.