Whenever another creature you control enters, Kefka Palazzo deals 2 damage to each opponent
Past in Flames is a staple in both Modern and Legacy, Cabal Therapy is a Legacy all-star, Conflagrate has finished many a game for Modern Dredge, Ancient Grudge is a sideboard staple, and the list goes on, including Lingering Souls, Roar of the Wurm, Dread Return, Unburial Rites, Desperate Ravings, Deep Analysis, and Faithless Looting
Thats water bug and diving beetle erasure if you ask me
An extra turn might not seem that amazing considering you won't have much mana left the turn you cast this, but the real power is that it gives you the opportunity for all your other creatures and planeswalkers to provide extra value
Players collect points by first playing (win or lose), bringing a friend to game night or teaching someone the rules, then redeeming those points for a chance to win a prize
Being able to return creatures to the battlefield each turn, even in lieu of haste, is going to ruin a lot of opponents days