In DotA 1, casting it on creeps owned by Chen returned them instantly, and casting them on Allies that were Heroes (that had -disablehelp disabled) set a timer that teleported them back after a delay. Casting it on any other allied creep, whether owned by the Sentinel or by other players, put the spell on cooldown with no effect. In Dota 2, it treats Allied Creeps as Allied Heroes instead, and sends them back after a delay.