Epiphany (7) minimum with 2 Crystal Block and Bulwark Talent 38+. this gives Block Cap +81%, +100% when Bulwark is active. make sure your two Crystal Blocks equal 81% or higher.
Epiphany (8) maximum with 2 Crystal Block and Bulwark Talent 32+. this gives Block Cap +84%, +100% Block when Bulwark is active. make sure your two Crystal Blocks equal 84% or higher.
the reason you have 2 Crystal Block is that if you only have one, you would need 2 Epic Block to reach Cap.
Bulwark activates for 5 seconds when you Block an attack. if it deactivates after 5 seconds because you haven’t Blocked any attacks, you have to wait to Block an attack for it to activate again for the +100% Block.