How everytime when I meet in arena and my partner burst hum he always swap hp, when it should be forbidden. At first I even didn't know the name of the spell so I looked a bit in internet and saw that this is void shift. Link - > http://wow.gamepedia.com/Void_Shift and as patch log is saying, since 5.3 it shouldnt be use useable in arenas or rated bg's. But ofc in Warmane everyone can use it in arenas.
Well I guess spell specifics are based on early patch before 5.3. If not, then it's Warmane mistake for not fixing this. I am also seen some discipline priests to use it pretty active in arenas.
For Shadow Priests, cooldown has been increased to 10 minutes, up from 6 minutes, and the spell is no longer usable while in Arenas or Rated Battlegrounds.
Only shadow priests cannot use in arena/rated bg. Holy and Discipline priests can.
You have to learn to swap properly, or cc the priest at low hp while your burst gets ready again. It's really not that much of an issue if you're able to swap quickly and effectively with your partner.