Emstidor, yep T7 savage still have that mechanic with petrification. T7 too before the nerf.

About stop, alexander use it (Time stop), all buff have timer stop and you can't do anything except wait for damage (in savage). It's a mechanic too so not the end of the fight.
As an ability for players that would probably work like a stun with a stop on gcd/aa timer, like a enchanced stun. But will probably not work on MOST boss. That would be redundant.