Well,that the point isn't it?If we can not win against them,Can we win against other threat in creation?.It would take several days, if not weeks of pure traveling just to reach their strongholds, and then you'd have to hunt down all their members, assuming you even win.... that could potentially take ages and turn into a drawn-out, bloody quagmire, unless you want to travel with the Legion. But traveling with the Legion would take about 4x longer.
Of course, if you had Sorcery, you personally would be able to move faster, though the guerilla warfare issue is still a real one unless you get Heaven Sword Flash to work out to long / extreme range. But you guys don't have Four-Bladed Heavenly Emperor Stance.
Think of battle with them as measurement unit to test our ability.
Every plan no matter seem flawless in planning stage,alway need adjustment to made them reflect reality.
And the greatest assest of Luseng and creation is alway us.