User blog comment:ScalchopWarrior/Swampfire vs Heatblast?/@comment-24152851-20151130024723/@comment-24152851-20151201120952

You can't permanently kill him though. He'll keep regenerating, while Heatblast can't.

Freezing seems to be his only weakness, and even that's a short term solution since he can thaw himself out. Plus Heatblast can't do that.