Cloudstone Curio [Kaladesh Inventions] Gym Challenge Unlimited each player reveals their Main

each player reveals their Main Deck

and that player can't activate abilities that aren't mana abilities

Discard a card from your hand

Set: Legends Type: Creature — Demon Rarity: Rare Cost: {3}{B}{B} At end of combat

Cloudstone Curio [Kaladesh Inventions] Gym Challenge Unlimited each player reveals their MainSet: Kaladesh Inventions Type: Artifact Rarity: Mythic Cost: {3} Whenever a nonartifact permanent enters the battlefield under your control, you may return another permanent you control that shares a permanent type with it to its owner's hand. With innovative stabilizing techniques, Suja Pavani brings this piece of the sky itself to the Inventors' Fair.