2021-04-16 : If Retriever Phoenix somehow dies with its triggered ability on the stack, you may return it to the battlefield with that triggered ability.

2021-04-16 : If a card is brought into the game from outside the game, it will stay in the game until it ends or until its owner leaves the game, whichever comes first.

2021-04-16 : If instructed to learn, you may do nothing. Discarding a card and putting a Lesson card into your hand are both optional.

2021-04-16 : If you bring a card into the game from outside the game in a Constructed tournament (or a Constructed game played under tournament conditions), you may select only a card from your sideboard. In casual Constructed games, the card comes from your collection.

2021-04-16 : If you bring a card into the game from outside the game in a Sealed Deck or Booster Draft event, you may select only a card that is in the card pool that you built your deck from.

2021-04-16 : Retriever Phoenix must be in your graveyard at the moment you’re instructed to learn if you want to use the last ability to return it to the battlefield.