The Capitoline Triad

Once you announce you’re casting a spell, no player may take actions until the spell has been paid for. Notably, opponents can’t try to remove historic cards from your graveyard.

A card, spell, or permanent is historic if it has the legendary supertype, the artifact card type, or the Saga subtype. Having two of those qualities doesn’t make an object more historic than another or provide an additional bonus—an object either is historic or it isn’t.

Effects that modify a creature’s power and/or toughness without setting it will apply to creatures you control no matter when they started to take effect. The same is true for counters that change a creature’s power and/or toughness.

An ability that triggers “whenever you cast a historic spell” doesn’t trigger if a historic card is put onto the battlefield without being cast.

If a card in your graveyard has {X} in its mana cost, X is 0 for the purpose of determining its mana value.

Lands are never cast, so abilities that trigger “whenever you cast a historic spell” won’t trigger if you play a legendary land. They also won’t trigger if a card on the battlefield transforms into a card with the legendary supertype, the artifact card type, or the Saga subtype.