Originally Posted by
kayfabe
As far as I can tell you don't actually need both tanks to have exceptional defense but it really helps if at least one does. For example, I cleared the map with Iris and Fedora as my only healers by using a level 40 Awakened Bernice up top and a maxed Sybilla on the bottom. That's a bit lavish, but it indicates to me that a silver heavy and a third healer should be alright even if it takes longer.