Afaik there are not API functions or events to support this so far.
We requested them already as you can see here:
https://www.esoui.com/forums/showthr...ighlight=block
But there is nothing implemented to be used so far, I think.
You could check the combat events if there is anything about incoming damage types = "block" or similar.
https://wiki.esoui.com/EVENT_COMBAT_EVENT
There is a abilityActionSlotType == ACTION_SLOT_TYPE_BLOCK
And in addition try something like the usage of EVENT_POWER_UPDATE (number eventCode, string unitTag, number powerIndex, CombatMechanicType powerType, number powerValue, number powerMax, number powerEffectiveMax) to check for stamina loss (CombatMechanicType == POWERTYPE_STAMINA) as the block happens.