18 cards where the cards meld

Argoth, Sanctum of Nature (The Brothers' War #256a)
Brisela, Voice of Nightmares (Eldritch Moon #15b)
Bruna, the Fading Light (Eldritch Moon #15a)
Chittering Host (Eldritch Moon #96b)
Gisela, the Broken Blade (Eldritch Moon #28)
Graf Rats (Eldritch Moon #91)
Hanweir Battlements (Eldritch Moon #204)
Hanweir Garrison (Eldritch Moon #130a)
Hanweir, the Writhing Township (Eldritch Moon #130b)
Midnight Scavengers (Eldritch Moon #96a)
Mishra, Claimed by Gix (The Brothers' War #216)
Mishra, Lost to Phyrexia (The Brothers' War #163b)
Phyrexian Dragon Engine (The Brothers' War #163a)
The Mightstone and Weakstone (The Brothers' War #238a)
Titania, Gaea Incarnate (The Brothers' War #256b)
Titania, Voice of Gaea (The Brothers' War #193)
Urza, Lord Protector (The Brothers' War #225)
Urza, Planeswalker (The Brothers' War #238b)

The message was clear to Sorin—time to search for something else.