Kumena, Tyrant of Orazca [Rivals of Ixalan Prerelease Promos] Alara Reborn Promos and the steel became greaves

and the steel became greaves

Flashback—{1}{U}

Goblins Type: Instant Rarity: Rare Cost: {3}{U}{U} You may exile a blue card from your hand rather than pay this spell's mana cost

Set: Judgment Type: Creature — Cat Beast Spirit Rarity: Rare Cost: {5}{G}{W} Trample

They only specify the consequences should you fail

Kumena, Tyrant of Orazca [Rivals of Ixalan Prerelease Promos] Alara Reborn Promos and the steel became greavesSet: Rivals of Ixalan Prerelease Promos Type: Legendary Creature Merfolk Shaman Rarity: Mythic Cost: {1}{G}{U} Tap another untapped Merfolk you control: Kumena, Tyrant of Orazca can't be blocked this turn. Tap three untapped Merfolk you control: Draw a card. Tap five untapped Merfolk you control: Put a +1 +1 counter on each Merfolk you control.