Rulings

• For both modes, the value of X is determined as the ability resolves.2023-04-14
• If you choose the first mode and there are no other attacking creatures, you’ll create a 0/0 Dinosaur token. Unless something else is immediately raising its toughness, the token will die. You won’t have time to respond with a spell or ability to try and save it. A similar situation occurs if the greatest power among other attacking creatures is 0 or less.2023-04-14
• Although the Dinosaur token enters the battlefield attacking, it was never declared as an attacking creature (for the purposes of abilities that trigger whenever a creature attacks, for example).2023-04-14
• You choose which player, planeswalker, or battle the Dinosaur token is attacking. It doesn’t have to be the same player, planeswalker, or battle that Ghalta and Mavren is attacking.2023-04-14
• If you choose the second mode and there are no other attacking creatures, you won’t create any Vampire tokens.2023-04-14