Dreamslayer vs Shadow King

The famous disembodied Justice League villain who wiped out his entire planet, vs one of Charles Xavier's most famous villains.

Who wins?

Probably Dreamslayer. His power is near limitless.

Should have gone with Cassandra Nova.

Dreamslayer mentally enslaves Martian Manhunter in Maxwell Lord's body.

That's Maxwell Lord's body, though. When Max first found out he had powers, he was able to nudge J'onn without him knowing about it, or being able to defend against it.

Dreamslayer had other powers though. Then again, so did Legion and Proteus, and Shadow King still ran them over.

SK beat True Legion?