The Brothers' War

Urza, Lord Protector | Legendary Creature | Human Artificer | Artifact, instant, and sorcery spells you cast cost {1} less to cast. {7}: If you both own and control Urza, Lord Protector and an artifact named The Mightstone and Weakstone, exile them, then meld them into Urza, Planeswalker. Activate only as a sorcery. | Ryan Pancoast

Saheeli, Filigree Master | Legendary Planeswalker | Saheeli | +1: Scry 1. You may tap an untapped artifact you control. If you do, draw a card. −2: Create two 1/1 colorless Thopter artifact creature tokens with flying. They gain haste until end of turn. −4: You get an emblem with "Artifact creatures you control get +1/+1" and "Artifact spells you cast cost {1} less to cast." | Aurore Folny

Mishra, Claimed by Gix | Legendary Creature | Phyrexian Human Artificer | Whenever you attack, each opponent loses X life and you gain X life, where X is the number of attacking creatures. If Mishra, Claimed by Gix and a creature named Phyrexian Dragon Engine are attacking, and you both own and control them, exile them, then meld them into Mishra, Lost to Phyrexia. It enters the battlefield tapped and attacking. | Chris Rahn

Sarinth Greatwurm | Creature | Wurm | Trample Whenever a land enters the battlefield, create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.") | Jesper Ejsing