WHM/MNK (this is not a troll)

[Korpg]

U need counterstance for it to be worthwhile so it wouldn't be good on a avatar

Ducal guard is insane on avatars making a avatar take 10% DMG from melee and 50% from magic or something

Avatars have always taken 50% damage from all forms of damage (except the element they are weak against).

Ducal Guard only adds more damage reduction to physical because avatars also have a 100% guard proc rate and the atma gives a superior damage reduction for guarded damage.

As for /MNK, you should try Roaring Laughter and Gnarled Horn, with counterstance up its insane.