Farshot Luck

Your luck borders on probability alteration. You gain 6 Serendipity dice. At level 1, this die is a d4. At level 5, the die becomes a d6. At level 10, a d8. At level 15, a d12. At level 20, a d20. As a reaction, you can roll a Serendipity die and add or subtract the number rolled to one ability check, attack roll, or saving throw that you made or that is targeting you. You can wait until after rolling before deciding to use the Serendipity die, but must decide before the DM says whether the roll succeeds or fails. 1d6 spent charges return at the end of a long rest.