"To the Death!"
continues in Defenders (1972) #10.
The Avengers and Defenders join forces to stop Dormammu, who uses the Evil Eye to merge his dimension with that of Earth. Like all good Super-Villain team-ups, Dormammu has reneged on his promise to restore Loki's sight, and instead imprisons Loki.
Doctor Strange transports both teams and a host of other heroes to the Dark Dimension where Dormammu weaves his magic. Uatu the Watcher is on hand to witness the spectacle, as the empowered Dormammu defeats all-comers in succession.
Only when his victory seems complete does Loki, who has freed himself, struggle with Dormammu for control of the Evil Eye. The Scarlet Witch manages one last Hex which turns the Eye on Dormammu, converting him to pure magic and uses Loki as a conduit to be pulled into the Evil Eye. Loki's vision is restored, but his mind shattered.