Caltrops [Urza's Destiny] Battle Academy Set: Dominaria Prerelease Promos Type:

Set: Dominaria Prerelease Promos Type: Legendary Sorcery Rarity: Rare Cost: {5}{W}{B} (You may cast a legendary sorcery only if you control a legendary creature or planeswalker

If that player chooses self

Set: Black & White: Boundaries Crossed Type: Metal Rarity: Holo Rare Retreat cost: 2

and it can block creatures with flying

Centuries ago

Caltrops [Urza's Destiny] Battle Academy Set: Dominaria Prerelease Promos Type:Set: Urza's Destiny Type: Artifact Rarity: Uncommon Cost: {3} Whenever a creature attacks, Caltrops deals 1 damage to it. Toward the end, Gatha struggled to keep his experiments in and his patrons out.