Revealed skills
A block can be too much, but that skill can grant a damage reduction from affected players, punishing them to be catch while in stealth.
A thing like 20-25% reduced direct and condi damage.
Reducing condition damage could also be what it does. I am not really sure about the direct damage decrease as we have Weakness and Protection doing that. I would prefer a unique effect for Revealed that is also impactful considering that it is short duration but cant be removed. Since people seem to struggle having unblockable skills or access to it, I thought this could fill that gap.