Underlord Rhaskos is a rival Underlord in War for the Overworld. He appears in Campaign mode and as an AI personality in Skirmish and Multiplayer modes.
In Campaign mode, Rhaskos has been pushed back from Kairos, and the Empire is beginning an assault on his Home Realm. Mendichaus orders Oberon to follow after them to defend Rhaskos. In Level 5, he is sent to one of Rhaskos's defeated dungeons, and instructed to claim its core. He must then initiate a Ritual (campaign only) to send one of his Dungeon Cores into Rhaskos's Home Realm. During the Ritual, a number of dwarves come in to make things difficult, however Oberon eliminates them and proceeds towards saving Rhaskos.
In Level 6, Rhaskos helps teach Oberon about using Beasts, while directing him to free his imprisoned Minions, stating that they would be more than happy to join his ranks and avenge their former master. Meanwhile, Mendichaus directs Oberon's forces towards a portal the Empire has established within Rhaskos's Home Realm, with instructions to destroy it. Oberon destroys this portal, and proceeds deeper into the realm to protect Rhaskos.
Rhaskos's final dungeon core is threatened in Level 7, and Mendichaus instructs Oberon to protect it at all costs. The goddess, Kira, is preparing to destroy him once and for all with the power of an artifact called the Aum. As she charges the Aum, she sends waves of dwarves at the Underlords. As Kira charges the artifact, Rhaskos begins to break down, seeming to remember something. He briefly mentions a life before this one, to which Mendichaus promptly tells him to be quiet. Despite the best efforts of Oberon, Kira manages to charge the Aum, and annihilates both dungeon cores. Rhaskos is banished back into the Aether at the completion of the level.
- Rhaskos's Dungeon theme is unlockable by completing the Campaign.
- His color in the campaign is Red.