01Overview
Rathma is a long, multi-stage encounter: you clear undead areas, beat Mendeln and Rathma one at a time, and then fight both together with a shared life pool. It is the only source of the Tainted Worldstone Shard, the one way to corrupt an Annihilus.
It is harder than Diablo Clone: poison, cold and magic damage from several directions, healing adds, Void Knight waves and a Bone Spear that scales with your life.
02Summoning
| Ingredient | Where it comes from |
|---|---|
| Splinter of the Void | The Shadow of Mendeln map event, which always drops one since Season 14 |
| Trang-Oul's Jawbone | Undead monsters in Hell (about 1 in 22,500); it can also drop inside the encounter's first stage |
| Hellfire Ashes or a Hellfire Torch | Cube a Hellfire Torch into stackable Ashes; spare wrong-class Torches are the usual source |
Cube the three into a Voidstone and use it at the Blood Fountain in Harrogath. Cube the Voidstone on its own to cycle tier 0, 1 and 2. Tier 0 gives three re-entry portals; tiers 1 and 2 give none but add exclusive drops. Your pre-buffs are removed and your mercenary dies when you enter.
03The six stages
| Stage | What you do |
|---|---|
| 1. Ruins of the Necropolis | Clear the area. Few potions drop here, so bring your own. |
| 2. Mendeln | Fight Mendeln alone. |
| 3. Decaying Swamplands | Clear the area. |
| 4. Rathma | Fight Rathma alone. |
| 5. Decayed Highlands | Clear Void Knights, Hydras and frogs; the portal onward is in one of three spots. |
| 6. Both together | Mendeln and Rathma share one life pool. |
Mendeln
- Sanguine Bearers: at 90, 70, 50 and 30% life, four blood golems walk to Mendeln and heal him. He is immune while they live, so kill them before they reach him.
- Poison sequence: at 80, 60 and 40% life he casts vines, Lower Resist and poison clouds at the arena edge, then a long poison nova.
- Other attacks: a poison orb, a sludge nova of direct poison damage, a cold wave, Lower Resist (stronger on higher tiers) and Ancient Spires that cast Glacial Spike.
- At 15% life he retreats and the stage ends.
Rathma
- Conjured Souls: below 80% life he summons souls that cast Fissure (fire).
- Void Knight waves: at 70, 50 and 30% life, waves of four, five and six Void Knights with cold, fire, poison and physical damage; they cast Amplify Damage and Lower Resist. Rathma is immune while knights live.
- Bone Spear: magic damage scaled to a percentage of your life. It leaves a damaging trail and cannot be blocked, evaded or dodged.
- Other attacks: Teeth and a bone nova that leaves a damaging ring.
- At 15% life he retreats.
The final fight
Both bosses share one life pool. Damage uses the resistances of the boss you hit, is halved, and is applied to both, so hit the boss with the lower resistance to your damage type. Poison sequences come at 80, 60, 40 and 20% shared life, Void Knight waves at 70, 50 and 30% (both bosses are immune while the knights live). There are no Bearers and no Spires in this stage. Season 14 fixed poison damage not being shared between the two bosses and poison length being cut on top of poison damage, so poison builds work properly here now.
04What you need
| Boss | Physical | Magic | Fire | Lightning | Cold | Poison |
|---|---|---|---|---|---|---|
| Rathma | 30 | 20-25 | 75 | 50 | 50 | 0 |
| Mendeln | 30 | 20-25 | 65 | 40 | 40 | 0 |
Both are monster level 110. Poison is their weak point; fire is their strong one.
- Poison and cold resistance well above 75%. Mendeln, the Void Knights and Rathma's Lower Resist all push them down; overcap every resistance you can.
- Fire resistance capped for the Fissure souls and fire Void Knights.
- Antidote and full rejuvenation potions, because the first stage drops few potions.
- Single-target damage plus a way to handle adds: the Bearers and Void Knight waves stop the fight until they are dead.
Builds that do it well
Blade Sentinel Assassin is the standout: easy on tier 0 and tier 2. On tier 2, Whirlwind Barbarian, Meteor and Blizzard Sorceress are moderate; Fire Druid and Desecrate builds such as the Poison Nova Necromancer find it hard. Melee and physical builds with high damage, such as Plague and Jab Javazons, Berserk Barbarians and Maul Druids, also do well.
05Rewards
- Tainted Worldstone Shard, guaranteed on every tier. Cube it with an Annihilus for one of five equally likely outcomes: +1 to all skills, extra Vitality and Energy, extra all resistances, extra experience, or the Annihilus turns into a random magic small charm. Only use it on a copy you can afford to lose.
- Tiers 1 and 2: a 1 in 200 chance at The Third Eye, Band of Skulls or Cage of the Unsullied.
- A separate roll for a utility item (Skeleton Key, Horadric Almanac or Horadric Navigator): 1 in 50 on tier 0, 1 in 44 on tier 1 and 1 in 38 on tier 2. It can drop together with a unique.