It´s often the initial damage that kills a dominator in big teams with just one dominator. Carrion Creepers does one lovely thing for a dominator: it draws aggro. If you start it first thing in a big battle it will take the initial damage until you have confused them and held those who got out of the Carrion Creepers area.
If you are fighting on a platform they will extend from the ground level through the platform to reach your foes.
If you finish a fight fast the creepers will follow you into the next fight as well - even if they have to take the elevator to get there
