Quote Originally Posted by aodhan_ofinnegain View Post
Blocking is a scaling mitigation, so minimum is 15% damage reduction at the start of the expansion, as you get better shields it will scale up to a maximum of 25% (formerly 30% but was nerfed along side parry by 5% in ShB). Current i450 King Shield blocks for 20% damage reduction.
Do you have any source that confirms maximum block strength of 25%?

According to this reddit thread maximum block strength is now 20%, minimum (worst shield) 10%.

Even with the highest possible shield in synced content I have yet to see any blocks higher than 20%.

@OP: Seraph522 did a really good explanation of the skill, their post has everything you need to know.
Tho... I haven't tried it on any guaranteed crit hits, might be useless against them...