Aug vs Furnace with Aquilas

Does anyone happen to know how much of a trade off there is from Aug vs a furnace. It seems like you open a skill slot and allows for better defense. But Im not sure how much if any offence you give up? Plz help

Roughly 63% damage vs elites using aug. You probably keep all your resources when in a group of stuff so I imagine you’d always have that 50% DR. Roughly 47% DR to elites with aug.