I've faced the 300% from Firebrand before. It was Firebrand/Iron-Man/Sent, and after the first time's novelty wears off, it's just... boring. Don't know why people don't run Firebrand/Iron-Man instead of Firebrand/Skrull. Much better assist, and out of like 100 attempts, I only escaped that shit once through X-Factoring.
It does make fighting Firebrand more intense in the neutral, though.
b/c skrull>>>>>iron man, and most IM players aren't good enough to do his infinite