Convention Maro

Whenever you cast a spell that [CHOICE A], create a green Elemental creature token named Maro with "This creature's power and toughness are each equal to the number of [CHOICE B]."
— As you create your deck, choose an [A] and a [B] —
• [A1] "is an Elemental" | [A2] "has a watermark or landscape orientation" | [A3] "targets a creature you control"
• [B1] "cards in your hand" | [B2] "card types among cards in your graveyard" | [B3] "artists among nonland, nontoken permanents you control"