This is by far the best custom you've made. It's probably worth more than 90.
I'd suggest limiting how many figures you can pick for Zombie Breath (maybe to 3?) and specifying what figures you can place instead (probably a previously destroyed Undead Savage).
And then I think I'd just change Zombie Flight to Stealth Flight since it's pretty similar to begin with.
But this is actually a quite good custom, keep it up.