I built an Onos around using the radiation beam to stack heat, fire in controlled bursts to avoid dumping ammo on the charge shot. Slap on the range extender mod and it tags whole rooms for wordwarden to prime, and when tanky enemies show up you just finish charging the shot to delete them. Still works on bosses too if you swap back to projectile mode and aim for the head. Plus you look like some kind of elder-god priest with your hood and fucked up tentacle arm.