If Bards had to choose what the debuff on RoD was, and you can't choose the damage reduction debuff, what would you choose? The only thing I can see it being useful for is a big accuracy debuff (20-25%, maybe) or a low defense debuff like 10%. Accuracy debuff might make tanking even easier again (in which case you might as well give the damage reduction debuff back), so I'd pick low defense debuff.