First few rooms: solve orb puzzles to cleanse Astral nodes while other players fending off spawning enemies
Duo fight - Cerus & Deimos: try to keep them apart (strong groups can stack and cleave them together) and avoid stepping in red ground AoE (oils), quickly kill clones that spawn
Final Boss - Eparch: Main mechanic is collecting orbs to prevent him from self-buffing during breakbar phase, prioritize these - either have an orb collector or collect orbs appropriate for your build - listed below
Red (Rage): Spawned by Shockwave attack. If picked up, player +Damage dealt, +Damage taken. If Eparch absorbs, he hits harder. Green (Envy): Arrow wave attack. +Condi & boon duration. Eparch corrupts boons. These are the most important to pick up as boon corrupt can wipe runs! Blue (Despair): Fountain attack. -Damage dealt/taken. Eparch takes less damage. Ideally a support takes these. Purple (Malice): Shard target AoE. +CC power, adds self-conds. Eparch inflicts extra condis. Orange (Gluttony): Vacuum pull. Heals you initially but hurts over time. Eparch heals himself.
Jump over shockwaves, run out when boss vacuums, dodge through arrow wave, dodge fountain projectiles, If targeted by red circle shards keep away from group
Quickly CC breakbar when it shows up, during it Eparch absorbs orbs on ground and orb buffs players have picked up