Luck of the Wandering Mage

All those years of wandering and exploring continents, strange new realms, and planes has taught you a thing or two.  Your endeavors have given you the Luck of the Wandering Mage.  Spend a 9th level spell you have prepared and you can reroll any failed roll and add your INT modifier to the new roll.  On a successful roll the spell returns to you after a long rest. Roll a natural 20 on your new roll and the spell comes back to you instantly.  Fail your new roll and you permanently forget that spell and you will have to learn it again from a scroll or tome only. Feat can only be used once every 2 weeks. 

You can get this feat at level 16 but cannot use it till you learn level 9 spells at level 17.

With time and knowledge one can become lucky!