what is the craziest way you killed the bbeg

trapped a Lich in a magic circle, cast the Disco spell on him, and just walked out of the room so we don't risk breaking concentration.   It took 5 rounds after we left before combat ended.  

Quote from starlinvf >>

trapped a Lich in a magic circle, cast the Disco spell on him, and just walked out of the room so we don't risk breaking concentration.   It took 5 rounds after we left before combat ended.  

 Death by Disco. Not to be confused with Death by Karaoke.

In the first campaign I played with other people, the Rogue had this magic item and all we knew about it was that it was "evil jelly" (someone had a detect evil spell or something I think, and the jelly set it off). Several times we tried to get the Rogue to use it, and he would always respond, "I'm not wasting my evil jelly!"

Fast forward to the fight with the BBEG. We'd been warned he was immortal, and didn't really know how we were going to deal with him. As we walk into the room, the BBEG tries to get us to feed the evil jelly to an enemy of his (another immortal) who is currently incapacitated. But we trick him and instead give the second immortal some non-evil jelly, which revives him. Cue initiative.

The BBEG is monologuing, and the Rogue's turn comes up and he says, "I use my Ring of Telekinesis to fling the evil jelly into the BBEG's mouth." Rolls a nat 20 and gets an instakill. He did not waste the evil jelly.

Quote from Penke >>

In the first campaign I played with other people, the Rogue had this magic item and all we knew about it was that it was "evil jelly" (someone had a detect evil spell or something I think, and the jelly set it off). Several times we tried to get the Rogue to use it, and he would always respond, "I'm not wasting my evil jelly!"

Fast forward to the fight with the BBEG. We'd been warned he was immortal, and didn't really know how we were going to deal with him. As we walk into the room, the BBEG tries to get us to feed the evil jelly to an enemy of his (another immortal) who is currently incapacitated. But we trick him and instead give the second immortal some non-evil jelly, which revives him. Cue initiative.

The BBEG is monologuing, and the Rogue's turn comes up and he says, "I use my Ring of Telekinesis to fling the evil jelly into the BBEG's mouth." Rolls a nat 20 and gets an instakill. He did not waste the evil jelly.

Quote from Penke >>

In the first campaign I played with other people, the Rogue had this magic item and all we knew about it was that it was "evil jelly" (someone had a detect evil spell or something I think, and the jelly set it off). Several times we tried to get the Rogue to use it, and he would always respond, "I'm not wasting my evil jelly!"

Fast forward to the fight with the BBEG. We'd been warned he was immortal, and didn't really know how we were going to deal with him. As we walk into the room, the BBEG tries to get us to feed the evil jelly to an enemy of his (another immortal) who is currently incapacitated. But we trick him and instead give the second immortal some non-evil jelly, which revives him. Cue initiative.

The BBEG is monologuing, and the Rogue's turn comes up and he says, "I use my Ring of Telekinesis to fling the evil jelly into the BBEG's mouth." Rolls a nat 20 and gets an instakill. He did not waste the evil jelly.

 Using evil jelly for good.

Much different set of rules in 1e but at the end of one of our early adventures we met the bbeg, a vampire who was intended to trouble us many times in future sessions.  I had a Wild Mage, and a spell that created a Wild Surge.  As the vampire addressed us I told the DM I was casting that spell, the result was "10' of non-living matter vanishes" (vanish having a certain meaning in those rules). 

DM:  OK, the vampire falls in a pit and is angered. 

Me:  Wouldn't a vampire be considered non-living matter?

DM:  ...

Me:  ...

DM:  <starting to turn a bit red, drops his head to the table>  Um...I guess he would be...

The party:  Rejoices!