Kefnet the Mindful (Invocation) [Amonkhet Invocations] SM137 Set: Gladiator's Assault Card type:

Set: Gladiator's Assault Card type: Normal Trap Rarity: Ultimate Rare Activate only when your opponent's monster declares an attack

don't stop

Set: The Dark Type: Enchantment Rarity: Rare Cost: {2}{R} Nonbasic lands are Mountains

or another monster's effect

if your Spellcaster monster battles an opponent's monster (Quick Effect): You can reveal any number of Spells with different names in your hand

Kefnet the Mindful (Invocation) [Amonkhet Invocations] SM137 Set: Gladiator's Assault Card type:Set: Amonkhet Invocations Type: Legendary Creature God Rarity: Mythic Cost: {2}{U} Flying, indestructible Kefnet the Mindful can't attack or block unless you have seven or more cards in hand. {3}{U}: Draw a card, then you may return a land you control to its owner's hand.