Just use the Divination Wizard.
The concept is quite similar, you can reflavour the powers a bit, while keeping them mechanically the same.
Portent can be called "Time Mastery": The Timelord goes forth in time and sees what will happen, and because of that he can change the present.
I don't like what your player created at all. With a healer and loads of healing potions he never runs out of juice for their powers, when other characters can only cast those spells once or twice a day!
No no no no. Nope.
The DM should say Yes, sure... If it's something reasonable.