As an additional cost to cast this spell, you may waterbend 
.
You control target opponent during their next combat phase. If this spell's additional cost was paid, you control that player during their next turn instead. (You see all cards that player could see and make all decisions for them.)
Exile Secret of Bloodbending.
Illustrated by Barbara Rosiak · Avatar: The Last Airbender · #337
2025-10-02
While controlling another player, you also continue to make your own choices and decisions.
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Controlling a player doesn't allow you to look at that player's sideboard. If an effect instructs that player to choose a card from outside the game, you can't have that player choose any card.
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You can't make any illegal decisions or illegal choices—you can't do anything that player couldn't do. You can't make choices or decisions for that player that aren't called for by the game rules or by any cards, permanents, spells, abilities, and so on. If an effect causes another player to make decisions that the affected player would normally make (such as Master Warcraft does), that effect takes precedence. In other words, if the affected player wouldn't make a decision, you wouldn't make that decision on that player's behalf.
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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.
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You also can't make any choices or decisions for the player that would be called for by the tournament rules (such as whether to take an intentional draw or whether to call a judge).
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In a Two-Headed Giant game, gaining control of a player causes you to gain control of each player on that team.
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You only control the player. You don't control any of that player's permanents, spells, or abilities.
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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.
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The player you're controlling is still the active player during that turn.
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You can't make the affected player concede. That player may choose to concede at any time, even while you're controlling that player.
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Multiple player-controlling effects that affect the same player overwrite each other. The last one to be created is the one that works.
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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.
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You can use only the affected player's resources (cards, mana, and so on) to pay costs for that player; you can't use your own. Similarly, you can use the affected player's resources only to pay that player's costs; you can't spend them on your costs.
was spent to cast this spell, instead create a token that's a copy of that permanent, except the token has "When this token enters, if it's a creature, it fights up to one target creature you don't control."
rather than pay this spell's mana cost.
. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for 
.)