Will-o'-the-Wisp

Flying (This creature can't be blocked except by creatures with flying or reach.) : 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.)

"About, about in reel and rout The death-fires danced at night; The water, like a witch's oils, Burnt green, and blue and white." —Samuel Coleridge, "The Rime of the Ancient Mariner"