Was running from an orb and kept running from it when I moved, quite a few times dangerously near other players (though I was trying to avoid that), the orb eventually started to activate and then stopped almost immediately (or does that count as immediately?) when there were no targets in range (unless you counted me). For the rest of the fight, I was tethered to the orb and had no bad effects target me. Other players could see it, but it never activated for any of them.