Delirium as a "save skill" button. When five GCDs are saved the button changes to Living Shadow.
When activated the Living Shadow will burst out and use the saved skills in order. Skills don't cost you resources, but will gain them for you if the skill it uses would. i.e if you saved a soul eater, when the shadow uses it you'll gain blood and HP.
That seems like it could be fun to me, would give you some stuff to think about, and it isn't copied from another job.
Ability costs, amount of GCDs required, potencies, etc. might need adjusting. This is just a basic frame of an idea
