714.3 Sagas use lore counters to track their progress.
714.3a
Each Saga without read ahead has the intrinsic ability “This Saga enters with a lore counter on it.” This ability creates a replacement effect (see rule 614.1c).
(refs: 614.1c)
714.3b
Each Saga with read ahead has the intrinsic abilities “As this Saga enters, choose a number between one and this Saga’s final chapter number” and “This Saga enters with the chosen number of lore counters on it.” (See rule 702.155, “Read Ahead.”) These abilities create replacement effects (see rule 614.1c).
(refs: 702.155, 614.1c)
714.3c
As a player’s precombat main phase begins, that player puts a lore counter on each Saga they control with one or more chapter abilities. This turn-based action doesn’t use the stack.