Lurrus of the Dream-Den

Apr 17, 2020 · Once you begin to cast the spell, losing control of Lurrus won't affect the spell. You can finish casting it as normal.

Apr 17, 2020 · If you cast one permanent spell from your graveyard and then have a new Lurrus come under your control in the same turn, you may cast another permanent spell from your graveyard that turn.

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 · Lurrus doesn't let you play lands from your graveyard.

Apr 17, 2020 · You must pay the costs to cast that spell. If it has an alternative cost, such as a mutate cost, you may cast it for that cost instead.

Apr 17, 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.

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 · If a card in a player's deck has {X} in its mana cost, X is considered to be 0.

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.

Apr 17, 2020 · Before shuffling your deck to become your library, you may reveal one card from outside the game to be your companion if your starting deck meets the requirements of the companion ability. You can't reveal more than one. It remains revealed outside the game as the game begins.

Apr 17, 2020 · If a permanent card is put into your graveyard during your main phase and the stack is empty, you have a chance to cast it before any player may attempt to remove that card from your graveyard.

Jun 1, 2020 · Once you put your companion into your hand, it behaves like any other card you’ve brought into the game. For example, if it’s countered or destroyed, it’s put into your graveyard, remaining in the game.

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