Secret of Bloodbending

While controlling another player, you make all choices and decisions that player is allowed to make or is told to make. This includes choices about what spells to cast or what abilities to activate, as well as any decisions called for by triggered abilities or for any other reason.

If the targeted player skips their next combat phase or turn, you'll control the next combat phase or turn the affected player actually takes.

Multiple player-controlling effects that affect the same player overwrite each other. The last one to be created is the one that works.

While controlling another player, you can see all cards in the game that player can see. This includes cards in that player's hand, face-down cards that player controls, and any cards in that player's library the player may look at.

If a waterbend cost is part of the total cost to cast a spell or activate an ability, you may tap an untapped artifact or creature you control rather than pay one generic mana in that total cost any number of times up to a maximum of the amount of generic mana in the waterbend component of that total cost.

If an artifact or creature you control has a mana ability with {T} in the cost, activating that ability while casting a spell or activating an ability with waterbend will result in the artifact or creature being tapped before you pay the spell's costs. You won't be able to tap it again for waterbend. Similarly, if you sacrifice an artifact or creature to activate a mana ability to pay a cost with waterbend, that artifact or creature won't be on the battlefield when you pay the spell's costs, so you won't be able to tap it for waterbend.