The dissonance of design in Deep Dungeons

[Valence]

Generally the idea could be cool, but not in form of some lost actions or whatever.
I would like to see actions have additional effects that dont work on bosses, like doton applying heavy on mobs or arm's length applying slow.
There used to be a lot of poisons we could use apply status effects on mobs. Blind, paralasys, silencing, heavy etc are all present in game but underutilised.
So i think having your regular actions getting additional effects could prove very fun and would benefit deep dungeons and it would lead to more interesting defence oriented rotations.
For example if blm's ice spells applied stacks of freezing that would transform to deep freeze status if you applied several stacks fast enough. While its not optimal damage, it would give blm a powerful defense mechanism.

Yes I agree with that. That's also why I brought up the pvp model because it seems a lot more suited to deep dungeons that what pve currently offers. I'd definitely like having unique effects coming from tools beyond just "damage", rewarding players to play more tactically depending on the situations they face at any time.
Taking your BLM example you could have stuff like Wreath of Ice which is essentially an ice spikes or a life steal on xenoglossy/foul.