the nature modifier randomizes the nature and 1 iv reroll, you can only reroll 1 iv stat (you get to select one iv, not as affective as the iv rerolls) for if you have more than 1 bad stat
getting to select the specific IVs that are rerolled would be considerably more beneficial than the current reroll-all that we have.
also i think natures still arent affecting stats, but mints would be nice if/when they do.
