Two things:
REALLY long charge distance, given there's LoS to the target of your charge
If you get behind the enemy, they are a real pain in the ass because of the command modifier they impose for being within 20cm. The enemy has to execute at least two orders to get rid of that cheap flier unit in his rear.
Remember that the Tomb King has an unlimited command distance too, so it's not out of the realm of possibility to order the carrion in from far away.