... too simple build, I fear. Legs and torso are really basic. The arms go in the right direction, though. I like the look of the Ehlek head inside the chest. Also I really appreciate the use of Mata green.
But you really should make the MOC have the complexity of a titan build - which is most easily achieved by making limbs and torso more custom built. Currently he might look like a set streight out of 2008, but ideally he should rather reach the complexity of MOCs like these:
Also this . Although it would be totally ok, too, if you put, for example, a Miru on this MOC and declare it a Mask of Scavenging. That's totally acceptable for this project. Nonetheless, in this case I think I would prefer that you use the original idea for a mask power you had - simply to keep things more diverse.
As to the backstory:
Basically works, I guess, although I'm not a huge fan of him creating a second Kraata-Kal.
Rules and list in post 1
There are again Makuta to be assigned