Embrace the Darkness and Energy Shield works separately.

If the damage higher than unreserved darkness, it bypass energy shield and hit directly to darkness + hp. But if I have no darkness - energy shield works fine and the damage taken from hp + es.
Here is the example:
I have approx 1.1k hp, 400 darkness and 200 es. Damage taken is 800.
Expectations: 900 hp, 0 darkness, 0 es
Reality: 700 hp, 0 darkness, 200 es

If the damage is more than hp + darkness I would die without any use of es no matter how much is it.

p.s. The above applies to damage from one hit.

Agreed. Monsters that otherwise seem to deal normal physical damage (and aren't applying any ailments with the hit) are bypassing Energy Shield sometimes. I suspect in the recorded example the hit happens to coincide with refreshing another instance of Darkness reservation, but the hit itself would've done slightly more than 100 damage.

Apparently, my HC character died from that bug today. In its current state, Darkness doesn't contribute to one-shot defense, and the time your Darkness depletes in one hit—you should get rid of it or play without ES at all, sadly. It would be nice if this were added to the known issues