Season 15's core mechanic requires picking one of three Splinters (Terror/Diablo-Fire, Destruction/Baal-Cold, Hatred/Mephisto-Physical/Shadow), each granting a distinct auto-triggering Iconic Power AND modifying a different set of endgame activities (Helltide, Infernal Hordes, Tree of Whispers, The Undercity, Nightmare Dungeons, The Pit) - and the choice locks for a meaningful period before a follow-up unlock lets you swap.
Each Splinter has its own reputation track (6 upgrade tiers at 350/1,300/5,150/13,100/17,400/20,000 reputation, plus 8 activity modifier ranks) that is tracked separately and NEVER lost when you swap, so re-choosing later doesn't reset prior progress on a Splinter you return to. Swapping itself requires re-acquiring a Splinter of Evil from a Capstone-tier Waking Nightmare, not a menu toggle.
The system is designed to reward committing to farming the activities your chosen Splinter buffs (its own listed 'modifies_activities') rather than switching reactively, since the swap has real friction (a boss-tier dungeon clear) even after it unlocks.
Reputation upgrade thresholds: 350 / 1,300 / 5,150 / 13,100 / 17,400 / 20,000 (identical structure across all three Splinters).
Pick your Splinter based on which endgame activities you actually plan to farm this season, not purely on the Iconic Power's raw damage type, since the activity modifiers compound with your farming route every run.
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