D'lirium Ost: Gestas Boss Battle - 30 (BETA) 

It will be better if you ask about this Delirium developers. These soundtracks keeps in main Ost pack but some track aren't added in the game. May be these soundtrack will be used in next D'lirium game: the golden rogue.

​@@unfaithful796Oh! They're making a sequel? Very nice!

They have been developing a sequel for a long time, but no one knows any information about the development or release date.