you need 4 piece set, thats the first thing you buy for EoF. Set bonuses just overpower those few stats gained from 264ilvl. Also you will upgrade it with Tokens (251 -> 264 -> 277)
If you have 4 set t10 already, sure, you can get that chest, because mages don't use T10 chestpiece, they use
https://wotlk.evowow.com?item=50629, so you will need some EoT trinket with Hit rating or gem it or something.
Note that chest has low competition for it - only mages use it I think, so you will get it as it drops.