Here are some dark and cool agency name ideas for your hero-themed concept, "Ultra Rumble Academy":
- Eclipse Agency
- Shadow Nexus
- Void Vanguard
- Obsidian Legion
- Specter Society
- Nightshade Alliance
- Phantom Enclave
- Cinder Protocol
- Grim Arsenal
- Nebula Syndicate
Feel free to mix and match words or use them as inspiration to create the perfect name for your agency!