Well, no, since it's a clearly written class feature that doesn't mention anything to do with DM discretion. Except in the sense that everything is DM discretion, but in that case discussing any rules at all is pointless.
First off, you’re relying entirely on spells you have no guarantee of ever getting. You’re a wizard. You don’t get to just choose spells willy nilly. You find those and you copy them into your book or you learn from some other means. No guarantee of those means.
What?
Wizards can choose two spells each level without having to find them.
Antimagic field is an eighth level spell with one hour concentration duration; an item that has it on 24 hours a day would easily be a legendary item. People underestimate how powerful a spell it is and suggest spamming it everywhere. Having it on every door, window, sewer pipe, and vent would be massive overkill just to spite wildshape.
Thanks to UA warforged and generous magic item allowances (a staff of power and +2 shield I think were the relevant ones for AC) I had a wizard with 28 resting AC (33 with shield).
More importantly, don't wish for anything that big; keep it in a similar power level to the example wishes. Precise wording won't save you from "the wish might simply fail".
Well, no, since it's a clearly written class feature that doesn't mention anything to do with DM discretion. Except in the sense that everything is DM discretion, but in that case discussing any rules at all is pointless.