Boast

Boast
[[File:{{#setmainimage:MTGA Boast.png}}|70x70px]]
Keyword Ability
Type	Activated
Introduced	Kaldheim
Last used	Lost Caverns Commander
Reminder Text	Boast — [Cost]: [Effect] (Activate this ability only if this creature attacked this turn and only once each turn.)
Storm Scale	6
Statistics	15 cards 26.7% 26.7% 40% 6.7%
Scryfall Search
keyword:"Boast"

Boast is a keyword ability introduced in Kaldheim.

Description

Boast keyword adds a drawback to an activated ability which is referred as the boast ability. The drawback is as follows: a player can only activate the boast ability after the creature with the ability attacks and at most once each turn. Boast abilities can be activated during combat or even after combat — any time in the turn after the creature was declared as an attacker.

Boast takes the essence of the failed mechanic Inspired and the untap cost and simplifies them: creatures get abilities after they've attacked, promoting proactive gameplay and allowing blocking as a counterplay. Unfortunately, the templating as a downside of "only if it could attack" hurt its popularity, and despite the reasonable design and development space it only rated at a 6, slightly higher than Inspired and Untap, but not by much.

Cards interacting with Boast

• Birgi, God of Storytelling allows a second Boast ability activation.
• Dragonkin Berserker reduces Boast abilities by for each Dragon you control.

Rules

From the glossary of the Comprehensive Rules (June 7, 2024—Modern Horizons 3)

Boast

A special kind of activated ability that can be activated only once each turn if the creature with the boast ability attacked that turn. See rule 702.142, “Boast.”

From the Comprehensive Rules (June 7, 2024—Modern Horizons 3)

• 702.142. Boast
  • 702.142a A boast ability is a special kind of activated ability. “Boast — [Cost]: [Effect]” means “[Cost]: [Effect]. Activate only if this creature attacked this turn and only once each turn.”
  • 702.142b Effects may refer to boast abilities. If an effect refers to a creature boasting, it means its boast ability being activated.

Rulings

• A boast ability can be activated at any point after the creature with that ability has been declared as an attacker. This can be before blockers are declared, after blockers are declared but before combat damage is dealt, during combat after combat damage is dealt, during the postcombat main phase, during the end step, or, in some unusual cases, during the cleanup step.
• If it's not your turn and you gain control of a creature with a boast ability after that creature attacked, you can activate that creature's boast ability if it hasn't been activated yet that turn.
• If a creature with a boast ability is put onto the battlefield attacking, it was never declared as an attacker. Its boast ability can't be activated that turn.
• If an effect adds additional combat phases to a turn and a creature with a boast ability attacks more than once during that turn, its boast ability can still be activated only once.

Examples

Example 1

Arni Brokenbrow
Legendary Creature — Human Berserker
3/3
Haste
Boast — : You may change Arni Brokenbrow's base power to 1 plus the greatest power among other creature you control until end of turn. (Activate this ability only if this creature attacked this turn and only once each turn.)

Example 2

Varragoth, Bloodsky Sire
Legendary Creature — Demon Rogue
2/3
Deathtouch
Boast — : Target player searches their library for a card, then shuffles their library and puts that card on top of it. (Activate this ability only if this creature attacked this turn and only once each turn.)