Urza and Mishra were trained to look at ruins as questions. In the Caves of Koilos, that curiosity brought them to a machine from the Thran age and the power source at its heart. When the stone split, Urza emerged with the Mightstone and Mishra with the Weakstone. Each half strengthened its bearer while pulling toward the other.
The discovery did more than create a valuable artifact. It gave both brothers proof that the other possessed something incomplete yet essential. Cooperation could have reunited the stones, but rivalry made possession feel like identity. Giving up a half became indistinguishable from admitting that the other brother deserved the whole.
Koilos also concealed a doorway into Phyrexia’s history. Neither young scholar understood what had noticed them or how their excavation would connect Dominaria to an enemy built around conversion. The first danger was therefore not an army crossing a portal. It was knowledge arriving without the judgement needed to decide what should remain buried.