Mire Boa

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.) {G}: Regenerate this creature. (The next time this creature would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

Mire slime courses through its veins in place of blood. No sooner does it bleed than it opens its mouth to replace the loss.