Duskmourn: House of Horror

Leyline of Mutation | Enchantment | | If Leyline of Mutation is in your opening hand, you may begin the game with it on the battlefield. You may pay {W}{U}{B}{R}{G} rather than pay the mana cost for spells that you cast. | Sergey Glushakov

Growing Dread | Enchantment | | Flash When Growing Dread enters, manifest dread. (Look at the top two cards of your library. Put one onto the battlefield face down as a 2/2 creature and the other into your graveyard. Turn it face up any time for its mana cost if it's a creature card.) Whenever you turn a permanent face up, put a +1/+1 counter on it. | Maxime Minard

Oblivious Bookworm | Creature | Human Wizard | At the beginning of your end step, you may draw a card. If you do, discard a card unless a permanent entered the battlefield face down under your control this turn or you turned a permanent face up this turn. | Josh Newton

Zimone, All-Questioning | Legendary Creature | Human Wizard | At the beginning of your end step, if a land entered the battlefield under your control this turn and you control a prime number of lands, create Primo, the Indivisible, a legendary 0/0 green and blue Fractal creature token, then put that many +1/+1 counters on it. (2, 3, 5, 7, 11, 13, 17, 19, 23, 29, and 31 are prime numbers.) | Ekaterina Burmak

Marina Vendrell | Legendary Creature | Human Warlock | When Marina Vendrell enters, reveal the top seven cards of your library. Put all enchantment cards from among them into your hand and the rest on the bottom of your library in a random order. {T}: Lock or unlock a door of target Room you control. Activate only as a sorcery. | Magali Villeneuve

Haunted Screen | Artifact | | {T}: Add {W} or {B}. {T}, Pay 1 life: Add {G}, {U}, or {R}. {7}: Put seven +1/+1 counters on Haunted Screen. It becomes a 0/0 Spirit creature in addition to its other types. Activate only once. | Sean Murray

Lakeside Shack | Land | | Lakeside Shack enters tapped unless a player has 13 or less life. {T}: Add {G} or {U}. | Bartek Fedyczak