Actually, I'd take issue with the fact that it will damage you if played at full health. The card text says, "Heal yourself to maximum health minus 1." If you're already above that amount, it shouldn't have any effect at all - it says it'll heal you, not "set your HP to X." Miracle used at full health is a misclick or a misconception anyway, so I don't see why Zanz shouldn't implement a quick if-clause to stop that little side effect.