Conversion can only happen once. So that 25% from MoD is not getting converted into Acid.
Vit resistance doesn’t matter and is available in abundance, the +% dmg from MoD is negligible. The 12% OA is pretty much the only thing worth from it.
A Permanent 15% dmg absorption means that you essentially take 15% less dmg from all sources, which is kind of big on Pet builds since you only have such things and heals to keep you alive. And the extra Chaos res helps too.
Mogdrogen’s Ardor does not provide flat damage. And it does not outperform Bys’s Dom.
+80% to All Damage, +14% Crit Damage, +6% Total Speed
vs
+45% to All Damage, +10% Crit Damage, +15% Offensive Ability (+ 22-35 Chaos Damage, +200% to All Damage, +45% Total Speed)