He manages to impale Jojo pretty thoroughly a couple of times, and fill the room with hellfire a couple more, but Jojo and Deekin are actually very good at not letting people die, when they themselves haven't died immediately, which they don't seem inclined to allow to happen today.

When things start looking bad, he tries to teleport out. "I'm terribly sorry, but I'm afraid I have another -"

"Thra'axfyl the Ambitious, you will face us."

The archdevil looks as if he might vomit. "Where did you learn that name."

"Die screaming," Garrus suggests, with another volley of arrows.

"Or take up crochet." She hits him with more stormbolts. She likes stormbolts.

He overextends himself trying to stab Belmarniss.

Jojo kicks the ranseur out of his hand and tosses it several feet behind him. Then he delivers a kick that sends the archdevil sprawling to the floor.

"Belmarniss? I think you should be the one to quash his essence. Quickly."

(The concept, which may have seemed abstract before, unfolds in her mind. It's more or less just - telling him why he should cease to exist. In great detail. And then sealing it with his True Name.)

"You repulsive, conniving waste of space, you and your legal loophole can both cease to share an ontological status with me and my friends and particularly deserving squirrels. All this fucking around and existing you're doing, cut it the hell out, Thra'axfyl the Ambitious."

Mephistopheles listens. He has to.

The light of life fades from his eyes. Then... there's something glowing, deep inside him. His form collapses into ash, except for a glowing spark.

It pulses with energy. Once, twice.

Jojo's eyes widen. "It's going to-"

Everything goes very bright.

Then everything goes very dark.