Mesarthim, the Captive

Islandwalk

Whenever you attack, up to one target creature gains islandwalk until the end of the turn, if it's a mystic, draw a card.

Put a -0/-1 counter on Mesarthim: Regenerate up to one target creature.

They say that a mermaid lives in that mansion, but I don't know how she can be happy like that...