Well, if you consider it logically, you are A) Not guaranteed success, and B) Making your spell, in essence, less powerful.
As a DM, I would allow you to make your spell less powerful for free, personally, but this is the mage paying a fairly large cost(a feat) for the ability to sometimes make their spells worse.
Yes, I know, it means you can sometimes fireball and miss the fighter, but really, it also means sometimes you fireball him when you wouldnt have, and at the cost of one of your feats.
I really like the flavor of this stuff, Bob, but I am gonna recommend this again: Why not give these abilities out every 3 levels that your player sticks with the specialist wizard?
So at level 3, they get reduce spell, at level 6 they get expand spell, at 9 they get whatever, etc. The abilities arent much better than flavor, they ARE flavorful, and do make you a more interesting evoker, but most of them arent powerful enough to take as a feat. I really think they have a place, but I dont think its the place you are assigning them.
If you made a 20 level Evoker Specialist Progression, and slid these in around the free feats, you'd have something special, I think.
Dont leave out the generalist, either, if you do go with this suggestion, though.
As a DM, I would allow you to make your spell less powerful for free, personally, but this is the mage paying a fairly large cost(a feat) for the ability to sometimes make their spells worse.
Yes, I know, it means you can sometimes fireball and miss the fighter, but really, it also means sometimes you fireball him when you wouldnt have, and at the cost of one of your feats.
I really like the flavor of this stuff, Bob, but I am gonna recommend this again: Why not give these abilities out every 3 levels that your player sticks with the specialist wizard?
So at level 3, they get reduce spell, at level 6 they get expand spell, at 9 they get whatever, etc. The abilities arent much better than flavor, they ARE flavorful, and do make you a more interesting evoker, but most of them arent powerful enough to take as a feat. I really think they have a place, but I dont think its the place you are assigning them.
If you made a 20 level Evoker Specialist Progression, and slid these in around the free feats, you'd have something special, I think.
Dont leave out the generalist, either, if you do go with this suggestion, though.