The Brothers' War

Hurkyl's Final Meditation | Instant | | As long as it's not your turn, this spell costs {3} more to cast. Return all nonland permanents to their owner's hands. End the turn. (Exile all spells and abilities from the stack, including this card. The player whose turn it is discards down to their maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.) | Nephelomancer

One with the Multiverse | Enchantment | | You may look at the top card of your library any time. You may play lands and cast spells from the top of your library. Once during each of your turns, you may cast a spell from your hand or the top of your library without paying its mana cost. | Liiga Smilshkalne

Arcane Proxy | Artifact Creature | Wizard | Prototype {1}{U}{U} — 2/1 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.) When Arcane Proxy enters the battlefield, if you cast it, exile target instant or sorcery card with mana value less than or equal to Arcane Proxy's power from your graveyard. Copy that card. You may cast the copy without paying its mana cost. | Kekai Kotaki

Depth Charge Colossus | Artifact Creature | Dreadnought | Prototype {4}{U}{U} — 6/6 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.) Depth Charge Colossus doesn't untap during your untap step. {3}: Untap Depth Charge Colossus. | Daniel Ljunggren

Hulking Metamorph | Artifact Creature | Shapeshifter | Prototype {2}{U}{U} — 3/3 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.) You may have Hulking Metamorph enter the battlefield as a copy of an artifact or creature you control, except it's an artifact creature in addition to its other types, and its power and toughness are equal to Hulking Metamorph's power and toughness. | Diego Gisbert

Spotter Thopter | Artifact Creature | Thopter | Prototype {3}{U} — 2/3 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.) Flying When Spotter Thopter enters the battlefield, scry X, where X is its power. | Michael Phillippi

Terisian Mindbreaker | Artifact Creature | Juggernaut | Whenever Terisian Mindbreaker attacks, defending player mills half their library, rounded up. Unearth {1}{U}{U}{U} ({1}{U}{U}{U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.) | Steve Prescott