This isn't completely right either. Shaman can ankh prior to reaching the brez cap(1 for 10 mans, 3 for 25), and not count. But once you cap out, the shaman in the raid can not ankh anymore.
ex/
In a 10 man, your resto shaman and off tank die. The shaman should ankh first, and then the tank can be Brezed by a resto druid or lock or DK.
If the tank was brezed first, then the resto shaman would not be able to ankh aftewards.
As to how Revival works currently in beta, it's a LoS instant cast super heal with near no mana cost at the moment. Very OP, and definitely will be tweaked.