Special Stages · Stage 2
Ultramarine Castle
禍々しき群青の城
Ultramarine Castle is a Battle Cats stage in Servant of Darkness. It costs 100 energy and sends 8 enemy spawn lines — led by Shadow Boxer K as the boss — against a 180,000 HP enemy base, and clearing it rewards 8,930 XP. Its enemies carry the Aku and Black traits, so cats that target them do the most work here.
Data updated: 2026-08-31
100Energy Cost
8,930XP Reward
180,000Enemy Base HP
5,400Stage Length
18Max Enemies
5.1Difficulty
Enemy spawns (8)
| Enemy | Strength | Count | First Spawn | Respawn | Base HP Trigger | Notes |
|---|---|---|---|---|---|---|
 Cerberus Kids | 100% | ∞ | 6.7s | 10s~13.3s | 100% | — |
 Doge Dark | 100% | 3 | 13.3s | 10s~16.7s | 100% | — |
 Aku Doge | 100% | 3 | 26.7s | 10s~13.3s | 100% | — |
| Doge Dark | 100% | 5 | 0.1s | 13.3s~20s | 99% | — |
| Aku Doge | 100% | 5 | 0.1s | 16.7s~23.3s | 99% | — |
| Aku Doge | 100% | 6 | 0.1s | 0.7s | 99% | — |
 Shadow Boxer K | 100% | 1 | 0.1s | — | 99% | Boss |
 Ms. Sign | 100% | ∞ | 900s | 900s | 100% | — |