Don't make it a 1 turn fuse for all detonators. If you do, they'll nerf the damage. They're terrible right now even with the damage, but you get more damage the longer the lead time is on the detonator (different toons have different length fuses on their detonators).
Instead, keep damage the same, but make 2 changes:
1. If any detonator goes off, all detonators on that character do. So maybe you have a bunch of 3-turn fuse detonators on a toon, and yo don't want to wait til the 6th turn for the last damage to be done. That's okay. On turn 3 when the first one goes off, it sets off the others.
2. When cleansed, a detonator has a 50% chance to explode and do damage immediately rather than being dispelled. Each detonator is checked separately, but if any explode, they all do because the one going off sets off the others.