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
3.5 LSV
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
1.0 LSV
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
3.5 LSV
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
3.0 LSV
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
2.0 LSV