Arcum's Whistle — ruling 1

If a turn has multiple combat phases, the ability can only be activated before the beginning of the declare attackers step of the first combat phase in that turn.

Arcum's Whistle : règles, fonctionnement et interactions (MTG)

Arcum's Whistle 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

, : Choose target non-Wall creature the active player has controlled continuously since the beginning of the turn. That player may pay , where X is that creature's mana value. If they don't pay, the creature attacks this turn if able, and at the beginning of the next end step, destroy it if it didn't attack this turn. Activate only before attackers are declared.

How it works : Arcum's Whistle

Original English text — Wizards of the Coast / Scryfall

#1September 20, 2013· Wizards of the Coast
If a turn has multiple combat phases, the ability can only be activated before the beginning of the declare attackers step of the first combat phase in that turn.
No other card is named in this ruling.