Originally Posted by
eschatological
Timers for things like Stampede and Dire Beast will always be a pseudo-timer. You track the cast of the spell, then just simply count down the known duration of the spell, as explained above. The weakness of this method is that the spell you're tracking summons a creatur(s) which can die. If they died, the aura wouldn't know, and would just continue counting down.
Usually not a problem in PvE, last ttime it mattered was heroic elite Protectors in T14 as Kaolan's pulse would just gib DB. But it's something to consider for PvP, where people might try and target your Stampede pets.