Library of Leng [Beta Edition] Unlimited Edition Creatures can't attack you unless

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you

Set: Beta Edition Type: Land — Island Mountain Rarity: Rare ({T}: Add {U} or {R}

you may draw a card unless that player pays {1}

using their libraries as their decks

Set: Kaladesh Inventions Type: Artifact Creature — Thopter Rarity: Mythic Cost: {0} Flying

Library of Leng [Beta Edition] Unlimited Edition Creatures can't attack you unlessSet: Beta Edition Type: Artifact Rarity: Uncommon Cost: {1} You have no maximum hand size. If an effect causes you to discard a card, discard it, but you may put it on top of your library instead of into your graveyard.