You're right. If Witherfingers would also heal yourself everybody would play Deception :D

I wanted to point out that these cards are comparable with their Roar: Both let your opponents sleep. Witherfingers just up to 3 creatures but this creatures will get Burn, a different way to damage creatures. Demo will damage one creature directly. If I would ask you what creature is an alternative to Demogorgon the answer would be Witherfingers.

But both cards have also a nice synergy together. I hope that I can get a 2nd Demo soon. 😉