Duskrib Stalker

When Duskrib Stalker enters the battlefield, roll a d20. 1–9 — Duskrib Stalker deals 2 damage to target player. 10–14 — Target player mills three cards. 15–20 — Target player reveals their hand. You may exile up to one artifact, instant, or sorcery cards from it. You may cast that card for as long as it remains exiled, and you may spend mana as though it were mana of any type to cast it.