Mother of Learning

1. Key pieces: they take the dagger and Quatach-Ichl's crown, with the lich's help in one restart, then beat him in another by pre-laying the battlefield, using Kael's soul-defense coins to banish him. The Chronology notes he also teaches Zorian pocket dimensions and tracking. The crown lets them make temporary six-restart loopers, who include Silverlake, Taiven and Kael.
2. Blantyrre: they sail the airship Pearl of Aranhal there, win lizardmen help, and send Daimen's group to find the staff, which is held by the dragon mage Violeteye. The staff gives six recall points.
3. Princess the hydra is tamed with the orb's control dagger, and the orb is studied as a Black Room to extend training time.
4. Chapter 89: the Gate is shown to put the loop inside the primordial Panaxeth. Panaxeth offers a deal, and Silverlake takes it, making a death pact and leaving the loop first. The Hope Spot of 'Victory' (all five pieces collected) turns catastrophic. Zorian and Zach then use the Gate and the orb to crack the primordial's cage and form an exit, while the Guardian is partly possessed by Panaxeth and Zorian's defective Controller marker is nearly stripped.
5. The wiki records that Taiven is killed by a beast formed from a piece of Panaxeth when the exit opens, and Kael is killed by the Guardian right after, so the exit has a cost. Zach leaves after a few more restarts.
6. The real world (about chapter 92 onward): one day before the festival, Zorian hits Iasku Mansion to rescue Raynie's brother. He recruits the Cyorian aranea, convinces Alanic of the time travel, and builds Mrva, a six-metre metal golem armed with a captured soulseizer chrysanthemum. The Red Robe, who is Jornak Dokochin, forces a truce with threats of dragon attacks and wraith bombs, and the dragon mage Oganj is bought off with the orb and crown.
7. The final battle: Mrva neutralises Quatach-Ichl, Silverlake is eaten by a grey hunter, and the Red Robe dies when his death pact with Panaxeth is not fulfilled. Zorian uses a spell inspired by the soulseizer to get past Zach's Mind Blank and traps him in an illusion in which every witness appears dead or mind-wiped, so Zach's angel contract is satisfied and he survives the month.

The month ends, the loop is over and both boys live. About a month later (chapter 107 per the wiki's references), Eldemar prepares to invade Ibasa, co-owns the Ibasan gate, and slowly accepts the aranea. Mrva is still not functional. Our sources do not give the series' final chapter number or its last scene, so the very ending is not verified.

No formal rank system. By the end, the wiki says Zorian has spent about 8.5 years in the loop excluding Black Rooms and over a decade in total, and Zach about 35 years (at least 1,008 loops). Per the author's comments cited on the wiki, Zorian can cast more than 60 magic missiles in a row at the end.