Use your imagination. For example, they have soul seeking rounds in their guns. Imagine a counter that charges up a super soul seeker shot and if you do something wrong it seeks you out for a one hit kill. I can also imagine a super teleporting captain that can blade slice everyone simoultaneously, there is a bunch of things to consider, hopefully they capitalize on all the cool stuff they can do. Fallen are similar to the Hive in the fact they can utilize a "soul" except they call it the ether, I can imagine super saiyan fallen as well using Kamehameha and spirit bombs as well. Death Totem, Deathsinger, and Oversoul are all Hive "Magic". They mastered whatever the soul is and use it as a weapon, the soul could be life force, light, or some other thing. Whatever it does it can make them immortal if manipulated but fragile to stronger beings of light, pretty much a stronger soul can dissipate a weaker one.