Thanks, Cloe! I think his shadow creature form is cute, too, in a Lovecraftian kind of way.
@Malandy: You can't lower the encounter rate with his field action--there's another way to do that in the game already. He can literally frighten things, which can be used to access new locations and goodies.
There are a couple of ways to prevent healing in the game, but those tend to impact the player more than enemies. When you fight him, he's probably going to suck your bloooood.