Iron Ward - Clarification

Just had a few questions about Iron ward since the gem description is a bit light on details:

"

While active, stores a percentage of the Physical damage that is prevented by your Armour or other sources of damage reduction.

I'm assuming this is only physical damage reduction which (as of 0.3.0) is armour (or evasion
if taking the "...and Protect me from Harm" notable from the Invoker), and doesn't take any other source of damage mitigation into account such as block.

Would increasing/decreasing damage taken (i.e. via shock) actually affect this how this skill functions, since it occurs after damage reduction?

(I'm just going off of what reading in the wiki - https://www.poe2wiki.net/wiki/Receiving_damage)

Also, is this damage scaleable at all? or is it like reflected damage where it cannot apply ailments, crit etc.?