Nice one, just what i need, but would be even better if you would be able to add few spells at once. 

Thanks. It was mainly meant as a way of adding specific spell abilities gained threw game play. It’s also a good way of adding epic bonuses or Devine favors.  

Ngl, feels way too vague. Also, RAW, this allows you to cast Wish at will

I understand that this is for ease and is not to be used as an actual feat, so I will upvote.