Reveal 1 monster in your hand, choose 1 monster from your Deck that has exactly 1 of the same Type, Attribute, Level, ATK or DEF, and banish the revealed monster from your hand face-down.
Then add, from the Deck to your hand, 1 monster that has exactly 1 of the same Type, Attribute, Level, ATK or DEF as the monster chosen from your Deck, and banish the card chosen from the Deck face-down.
You can only activate 1 "Small World" per turn.