We tell everybody to never stand on a circle, at any time, unless you are getting your colour. Once the colour disappears it is time to step off. Tanks also need to be very quick on taunting.
This, sans the taunting. Taunting doesn't have any really affect. He will randomly "Delete" a player if someone has run through a color that is not their own.
I've tried the taunting method before, taunting about .5 second before his shield drops so that I still have his aggro forced for 5 more seconds, he usually does Deletion within 3 after the shield drops and regardless of whether or not his Aggro is forced on myself or the other tank.