A Lighthouse in the Dark Now, there is a bright glimmer of hope in this murky, leech-ridden lake of despair
Since the Treasures are tapped, we can untap them with Archelos, Lagoon MysticArchelos, Lagoon Mystic or a similar card, or in some cases simply sacrifice the Treasures to Krark-Clan IronworksKrark-Clan Ironworks
Shard of the NightbringerShard of the Nightbringer having a cast trigger is a real disappointment with no way to get it back to hand, and Trazyn the InfiniteTrazyn the Infinite and Convergence of DominionConvergence of Dominion don't really do much in the deck
If you controlled it, return it to the battlefield tapped
This way, casting Kozilek, the Great Distortion, and other huge bombs is very much within reach
B keeps it during their turn, and then C regains control of the artifact once B's effect expires, then A will have it back after C's expires