Cavern of Souls [Modern Masters 2017] 270 When the chosen monster would

When the chosen monster would switch to defense mode during this turn

Set: Dark Revelation Volume 4 Card type: Effect Monster Rarity: Rare Attack: 2800 Defense: 2600 Effect: This card cannot be Normal Summoned or Set

Set: Champion Pack 7 Card type: Effect Monster Rarity: Super Rare Attack: 1500 Defense: 800 When this card is Special Summoned by the effect of a "Gladiator Beast" monster

except "Dupe Frog"

Cavern of Souls [Modern Masters 2017] 270 When the chosen monster wouldSet: Modern Masters 2017 Type: Land Rarity: Mythic As Cavern of Souls enters the battlefield, choose a creature type. {T}: Add {C}. {T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.