HORDA ZERO
Fallen Archangel is the boss associated with Empty Cathedral.
Normal campaign A0 keeps the simpler legacy boss loop. BossEncounterCatalog is activated for Ascension above A0, while the Expedition capstone boss always uses the advanced phase runtime even at A0.
Advanced phase 1 starts at 70% HP and repeats every 4s after its 1s telegraph. Creates 7 Void zones on a radius-132 ring; each zone has radius 42, lasts 2.4 s, and deals 42% of boss damage. Arena effect: Creates a shadow/Void zone on the target: radius 80, 1 s warning, 3 s duration, 50% boss damage.
Advanced phase 2 starts at 42% HP and repeats every 6s after its 1s telegraph. Summons 2 enemies, one on each side of the boss at ±64 units. Arena effect: Creates a shadow/Void zone on the target: radius 80, 1 s warning, 3 s duration, 50% boss damage.
Advanced phase 3 starts at 18% HP and repeats every 3s after its 1s telegraph. On first activation, permanently increases boss speed and damage by 15% for the encounter. Arena effect: Creates a storm/Void zone on the target: radius 80, 1 s warning, 0.3 s duration, 50% boss damage.