As soon as Fang Ze obtained those eight Absolute Pinnacle Divine Fiends, and began planning to ambush the Venerable, he had been contemplating which Venerable he should target.
Since the main goal of this ambush was to capture a Venerable, Fang Ze's first consideration was the success rate and the possibilities of escape if he failed.
He initially considered seriously inquiring around Heaven Beyond the Heavens to see if there was any Venerable who usually travels alone, recruited fewer demigods, and resided in relatively secluded places, then look for opportunities to make a move.
Alternatively, after the Blue Blood Venerable's forces were scattered, he could directly attack the Blue Blood Venerable.
But soon he dismissed these two ideas.