Block Damage vs Deflection

Does anyone know or have a guess how deflection will function vs Warbringer's 30% block damage? Will it reduce block damage by the 40% or do you always take the block damage no matter what other mitigation's you have?

Are you referring to Renly's Training? You still mitigate 100% of damage from blocked hits.

In any case you will
(1) Evade or not evade
(2) mitigate from deflection
(3) block or not block

There are significantly more steps in the receiving damage calculation, but GGG confirmed that you will deflect before mitigating via resistances, and resistances are calculated between evasion and block.

Wiki on Receiving Damage

The new turtle charm reads, "The Turtle Charm Notable Passive Skill no longer grants 25% less Block Chance, or Can Block Damage from all Hits while Shield is not Raised. Instead, it now provides You take 30% of damage from Blocked Hits, and Maximum Block chance is 75%.

So its no longer 100% mitigation. Based on what you listed above sounds like:

10k hit is reduced following order:

-Do you evade, No = 10k dam
-Did you deflect, yes = 6k dam
-Did you resist, yes (assume elemental at 75%) = 1.5k dam
-Did you block, yes (30% block dam) = 450 dam

Does this make sense?