After the shenanigans in Canterlot, the Mane 6 think they can rest easy with one god on their side and another on the loose. But Agni, the Hindu god of fire, has just been teleported to a world full of things to burn.
Illustrious primarch of the III Legion, turned renegade because the Imperium sucks. Experiencing pleasure unheard of and killing things since M31. Before that crusading and stuff.