Zirda, the Dawnwaker

Apr 17, 2020 · If more than one player wishes to reveal a companion, the starting player does so first, and players proceed in turn order. Once a player has chosen not to reveal a companion, that player can't change their mind.

Apr 17, 2020 · Effects that reduce the generic mana cost of an activation cost can't reduce that cost's colored mana requirements. The activation cost is reduced by only {1} if doing so reduces that cost to one mana. For example, a cycling cost of {2} would become {1}, and one of {1}{R} would become {R}. The activation cost is unaffected if it already costs one or zero mana (such as the activation cost of Zirda's last ability).

Apr 17, 2020 · An activated mana ability is one that produces mana as it resolves, not one that costs mana to activate.

Apr 17, 2020 · Permanent cards are artifact, creature, enchantment, land, and planeswalker cards. Land cards with basic land types have intrinsic activated mana abilities associated with those types.

Apr 17, 2020 · The companion's other abilities apply only if the creature is on the battlefield. They have no effect while the companion is outside the game.

Apr 17, 2020 · The requirements of the companion ability apply only to your starting deck. They do not apply to your sideboard.

Apr 17, 2020 · Your companion begins the game outside the game. In tournament play, this means your sideboard. In casual play, it's simply a card you own that's not in your starting deck.

Apr 17, 2020 · You may have one companion in the Commander variant. Your deck, including your commander, must meet its companion requirement. Your companion is not one of your one hundred cards.

Jun 1, 2020 · Paying {3} to put your companion into your hand is a special action. It doesn't use the stack and players can't respond to it. Once you take this action, you may cast that card if it's legal to do so before any other player can take actions.

Jun 1, 2020 · If you reveal a companion outside the game, for as long as it remains there, you may pay {3} any time you could cast a sorcery (that is, you have priority during your main phase and the stack is empty). Once you do, you put it into your hand and behaves like any other card you've brought into the game. For example, if it's discarded, countered, or destroyed, it's put into your graveyard, remaining in the game. This is a change from previous rules.

Jun 1, 2020 · Wizards of the Coast has issued functional errata for the Companion mechanic. Instead of casting companions from outside the game: Once per game, any time you could cast a sorcery (during your main phase when the stack is empty), you can pay {3} to put your companion from your sideboard into your hand. This is a special action, not an activated ability. It happens immediately and can’t be responded to. It can’t be countered or stopped by cards like Phyrexian Revoker. For more information please see https://magic.wizards.com/en/articles/archive/news/june-1-2020-banned-and-restricted-announcement