Katara, Bending Prodigy — ruling 1

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.

Katara, Bending Prodigy — ruling 2

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.

Katara, Bending Prodigy — ruling 3

Even if the cost of the spell or ability that waterbend is part of increases or decreases, you still may only tap artifacts or creatures to pay for costs up to the amount of the generic mana in the waterbend cost.

Katara, Bending Prodigy — ruling 4

You can tap any untapped creature or artifact you control to pay a waterbend cost, even one you haven't controlled continuously since the beginning of your most recent turn.

Katara, Bending Prodigy — ruling 5

"Waterbend [cost]" means "Pay [cost]. For each generic mana in that cost, you may tap an untapped artifact or creature you control rather than pay that mana."

Katara, Bending Prodigy : règles, fonctionnement et interactions (MTG)

Katara, Bending Prodigy is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

At the beginning of your end step, if Katara is tapped, put a +1/+1 counter on her. Waterbend : Draw a card. (While paying a waterbend cost, you can tap your artifacts and creatures to help. Each one pays for .)

How it works : Katara, Bending Prodigy

Original English text — Wizards of the Coast / Scryfall

#1October 2, 2025· Wizards of the Coast
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.
No other card is named in this ruling.
#2October 2, 2025· Wizards of the Coast
If an artifact or creature you control has a mana ability with 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.
No other card is named in this ruling.
#3October 2, 2025· Wizards of the Coast
Even if the cost of the spell or ability that waterbend is part of increases or decreases, you still may only tap artifacts or creatures to pay for costs up to the amount of the generic mana in the waterbend cost.
No other card is named in this ruling.
#4October 2, 2025· Wizards of the Coast
You can tap any untapped creature or artifact you control to pay a waterbend cost, even one you haven't controlled continuously since the beginning of your most recent turn.
No other card is named in this ruling.
#5October 2, 2025· Wizards of the Coast
"Waterbend [cost]" means "Pay [cost]. For each generic mana in that cost, you may tap an untapped artifact or creature you control rather than pay that mana."
No other card is named in this ruling.