He is an Alien variant of Dark Emperor Santa with much faster attacks and movement. He also warps cat units with every attack, which makes him a quite serious opponent. However, his range is much shorter.
Rover Cat has warp block, this helps a ton, plus it's cheap and has a decent cooldown. Perfect for protecting your attackers and debuffers against Satan Claus.
Because of fast attack and warp, it's hard to get rush units to kill it without something to block his warp.