Phase 1: Rune Barrage (100%-70%)
Aldur uses 4 skills: Fire Rune Barrage (fan of 5 fireballs, dodge between gaps), Frost Rune Nova (ring expansion, stay close), Lightning Rune Mark (marks player, 3s delay, keep moving), Chaos Rune Corrosion (ground DoT, avoid). Easiest phase, can be done hitless with practice.
Phase 2: Rune Guardian Summons (70%-30%)
Aldur summons 4 Rune Guardians (Fire/Ice/Lightning/Chaos). While guardians live, Aldur gains 80% damage reduction to their element. Kill the guardian matching your damage type first. Guardians drop supply runes (30% life + flask charge restore).
Phase 3: Full-Arena Rune Storm (30%-0%)
Most dangerous phase. Aldur becomes invulnerable and channels a full-arena rune storm. Safe zones appear randomly on the ground (~every 3s). Must stand in safe zones to survive. Channel lasts 30s, then Aldur enters weakened state for 15s (takes 50% more damage) — your DPS window.
Recommended Gear Threshold
Fire resistance 75%+ (mandatory), Cold res 50%+, effective life 4500+, at least one movement skill. Flasks: Life (instant), Ruby (fire protection), Quicksilver.