Mobile formations were formations that used moving objects as anchors, wether these objects be material, immaterial or conceptual.
This meant that Orion could use the blood forces of all the Lich lords and Leywos as the anchors so that as long as one person lived, the formation would still be up.
This perfectly complemented the third ability of the elemental formation, the Elemental Union function.
This function allowed for multiple things to happen like the sharing of overall power of the entire squadron.
This meant that at any given moment, Leywos could tap into the power of his entire squadron and make it his own or he could even sacrifice a Lich servant to revive himself as long as a shard of his soul was intact.
The formation also allowed Leywos to perfectly control the servants and their minds, allowing him to share some of his abilities among many other useful things.
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