The Brothers' War

Combat Thresher | Artifact Creature | Construct | Prototype {2}{W} — 1/1 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.) Double strike When Combat Thresher enters the battlefield, draw a card. | Victor Harmatiuk

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

Fallaji Dragon Engine | Artifact Creature | Dragon | Prototype {2}{R} — 1/3 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.) Flying {2}: Fallaji Dragon Engine gets +1/+0 until end of turn. | Filip Burburan

Heavyweight Demolisher | Artifact Creature | Construct | Menace At the beginning of your upkeep, tap Heavyweight Demolisher unless you pay {3}. Unearth {6}{R}{R} ({6}{R}{R}: 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.) | Svetlin Velinov

Iron-Craw Crusher | Artifact Creature | Wurm | Prototype {2}{G}{G} — 2/5 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.) Whenever Iron-Craw Crusher attacks, target attacking creature gets +X/+0 until end of turn, where X is Iron-Craw Crusher's power. | Filip Burburan

Su-Chi Cave Guard | Artifact Creature | Construct | Vigilance Ward {4} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {4}.) When Su-Chi Cave Guard dies, add eight {C}. Until end of turn, you don't lose this mana as steps and phases end. | Dmitry Burmak