Does earthen armour actually work?

[Jakuk]

Asuran Claws: Delivers a sixfold attack. Accuracy varies with TP.

Earthen Armor: Reduces any single action that would have taken over 75% of your maximum HP by 45%.
Multi-hit monster attacks do not count as a single action and will only proc if the individual hits exceed 75% of your character's HP, so it is still possible to be one-shotted by a multi-hit attack.

So if I had to guess, and assuming the mob move follows the BLU spell, it wouldn't work on Asuran Claws.