{U}: Rootwater Thief gains flying until end of turn. Whenever Rootwater Thief deals combat damage to a player, you may pay {2}. If you do, search that player's library for a card and exile it, then the player shuffles.
At the beginning of your upkeep, you may put a verse counter on Rumbling Crescendo. {R}, Sacrifice Rumbling Crescendo: Destroy up to X target lands, where X is the number of verse counters on Rumbling Crescendo.