Zied snapped him out of it. Then the Zilart showed up (a la Ocelot at the end of MGS2's Tanker chapter), emo'd about how they aren't perfect and that they have to kill everyone to be perfect, and summoned the Crystal Warriors to start by killing you. Raogrimm becomes the Shadowlord one last time to fight them knowing he will lose ("one does not have to be a prophet to foresee the outcome of this battle"), sacrificing his life to allow you to escape.
Back on topic: has anyone considered that the beastmen aren't after the elemental crystals used for synthing but the actual mother crystals? The established information about the shadowlord indicates he "fell into contact with a dark power resting beneath the northlands". Odin is a fantastic guess and the presence of his kindred army (and the scene of Emeline singing the lay to his crystal) pretty much confirms that they did work together very closely. HOWEVER, Odin's protocrystal is high up in Bearclaw Pinnacle, far from resting "deep beneath the northlands". However, the Vhazl shard IS resting deep beneath the northlands and it can be inferred that Diabolos is its guardian. Diabolos is a pretty dark power if you ask me, and he is the master of the dream world of Dynamis (the final you-don't-get-a-resting-place of the Shadowlord after he's finally killed for good, stated to be the result of a pact between him and Diabolos). Raogrimm mentions before he goes SSJ5 one last time that he "can still draw power from this land"; this seems to indicate that his shadowlord power came not from Odin but from the Vhazl crystal. It is further mentioned in one of the Snoll Tzar cutscenes that Raogrimm met up with Odin -after- he was already the shadowlord at that point, and it is suggested that he may have been manipulating or controlling him somehow.
So, assuming the facts we have now point to Raogrimm drawing his Shadowlord power from Vhazl, he must then be after the other shards for their power (he is as strong as he is now from just ONE shard- think of how much power he could have with even just one more). The Zilart also mention his existence causes quite a lot of "noise" in the crystals- perhaps a result of him drawing out their power?