Cut Short — ruling 1

Tapping a multicolored creature using convoke will pay for {1} or one mana of your choice of any of that creature's colors.

Cut Short — ruling 2

When calculating a spell's total cost, include any alternative costs, additional costs, or anything else that increases or reduces the cost to cast the spell. Convoke applies after the total cost is calculated. Convoke doesn't change a spell's mana cost or mana value.

Cut Short — ruling 3

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

Cut Short — ruling 4

Because convoke isn't an alternative cost, it can be used in conjunction with alternative costs.

Cut Short — ruling 5

You can tap any untapped creature you control to convoke a spell, even one you haven't controlled continuously since the beginning of your most recent turn.

Cut Short — ruling 6

Tapping an untapped creature that's attacking or blocking to convoke a spell won't cause that creature to stop attacking or blocking.

Cut Short — ruling 7

Once an ability of a planeswalker is activated, it doesn't matter if the planeswalker loses that ability. That planeswalker has still been "activated" that turn.

Cut Short — ruling 8

Emblems are separate from the planeswalkers you got them from. Activating an ability of an emblem doesn't cause any planeswalker to be "activated."

Cut Short : règles, fonctionnement et interactions (MTG)

Cut Short 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

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for or one mana of that creature's color.) Destroy target planeswalker that was activated this turn or tapped creature.

How it works : Cut Short

Original English text — Wizards of the Coast / Scryfall

#1January 12, 2024· Wizards of the Coast
Tapping a multicolored creature using convoke will pay for or one mana of your choice of any of that creature's colors.
No other card is named in this ruling.
#2January 12, 2024· Wizards of the Coast
When calculating a spell's total cost, include any alternative costs, additional costs, or anything else that increases or reduces the cost to cast the spell. Convoke applies after the total cost is calculated. Convoke doesn't change a spell's mana cost or mana value.
No other card is named in this ruling.
#3January 12, 2024· Wizards of the Coast
If a creature you control has a mana ability with in the cost, activating that ability while casting a spell with convoke will result in the creature being tapped before you pay the spell's costs. You won't be able to tap it again for convoke. Similarly, if you sacrifice a creature to activate a mana ability while casting a spell with convoke, that creature won't be on the battlefield when you pay the spell's costs, so you won't be able to tap it for convoke.
No other card is named in this ruling.
#4January 12, 2024· Wizards of the Coast
Because convoke isn't an alternative cost, it can be used in conjunction with alternative costs.
No other card is named in this ruling.
#5January 12, 2024· Wizards of the Coast
You can tap any untapped creature you control to convoke a spell, even one you haven't controlled continuously since the beginning of your most recent turn.
No other card is named in this ruling.
#6January 12, 2024· Wizards of the Coast
Tapping an untapped creature that's attacking or blocking to convoke a spell won't cause that creature to stop attacking or blocking.
No other card is named in this ruling.
#7April 14, 2023· Wizards of the Coast
Once an ability of a planeswalker is activated, it doesn't matter if the planeswalker loses that ability. That planeswalker has still been "activated" that turn.
No other card is named in this ruling.
#8April 14, 2023· Wizards of the Coast
Emblems are separate from the planeswalkers you got them from. Activating an ability of an emblem doesn't cause any planeswalker to be "activated."
No other card is named in this ruling.
#9April 14, 2023· Wizards of the Coast
A planeswalker was "activated" during a turn if one of its abilities was activated that turn. This includes its loyalty abilities and any other activated abilities it may have. That ability may still be on the stack, or it could have resolved, failed to resolve, been countered, or have been removed from the stack some other way.
No other card is named in this ruling.