It is a tense battle against the T'au and Mortarion is currently busy cleansing their lines of the living... Until he gets hit in the shoulder, the shot penetrating his rotten armor due to the T'au's sheer weapon strength.

"Damnation! Not even the gift of hotboxing my armor is granted!"

the smoke rising from his armor does show that he indeed has been using the rotten confines of it to create some sort of improvised hotbox, most likely to at least feel anything.

"IS NOTHING IN THIS CRUEL UNIVERSE SACRED!?"