Ball Lightning is a rare Creature — Elemental card from Mystery Booster 2 (MB2), collector number 130. Current market price: $0.51, TCGplayer market prices via Scryfall.
Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.) Haste (This creature can attack and {T} as soon as it comes under your control.) At the beginning of the end step, sacrifice this creature.