Eviscerate Skill cannot be used in Sanctum

Am I doing something wrong? I cannot meet the condition to allow me to use Eviscerate. I am clearly blocking since their hits apply no damage to me. Is this build not viable for the content?

Not exactly sure, but I would think counter attack's probably aren't going to work very well in sanctum as it revolves around trying not to get hit and you need to be getting hit, at least to be able to block for counterattacks.

In sanctum:

"

Defensive mechanics such as evade/dodge chance, damage reduction, block, spell suppression, and avoidance do not directly affect the loss of Resolve.

So the sanctum monsters won't be procing you block I don't think. I think there might be regular mobs in the sanctum that still might, but it doesn't seem very conducive to counter attack play to me. There might be a way to get it to work. I don't know for certain that there aren't counterattack builds doing sanctum.