This mod adds some music from TBOI to the game, such as, Infanticide, Pulso Profundum and Ascension.
There are 2 versions. (The difference is the stealth music)

Phases:

Stealth: Pulso Profundum
Control: Ascension 
Anticipation: Infanticide
Assault: Infanticide

Phases (V2):

Stealth: Everlasting Hymn
Control: Ascension
Anticipation: Infanticide
Assault: Infanticide

It requires Beardlib (I'm not sure) and SuperBLT.
Then just put the folder into "mod_overrides"

This is for a friend of mine, but I wanted to leave it here if somebody else wants it.