With your pitch, I imagined your game would be some kind of tower defense but seems to be more action focused with the main player doing the work. Not saying one is better than the other but it just surprised me.
With this combat focus, may I suggest taking some inspiration from the first Ratchet and Clank? In the first RaC, Ratchet is more fragile and less mobile than all the others, making the combat more puzzle focused as Ratchet needs to maximize the usage out of all his tools. Long range, crowd control, traps, luring enemies in, it was all in there