So actually we have try with a team of 5 people DH to use their "banes signets" with "Perfect inscription".
Details : We noticed than if you use bane signet in same time the last who used bane signet crushes the bane of others.
Example : 5 DH use banes signet with a short gap. First player who uses it : at 5 stack of banes signets, 2nd player : 4 stack, 3th player : 3 stack, .... & the last only 1 why ? because you crushe the old banes signets, so the fifth player before to use his bane signet had 4 stacks of banes signet & when he used it only 1. Normaly, everybody should have 5 stacks and not 5 4 3 2 1 stack.