Piercing Level

[Majimari]

Is it true that it's impossible for the enemy to have negative DEF or protection when the reduction from piercing exceeds their DEF or protection?

[Soluna]

Is it true that it's impossible for the enemy to have negative DEF or protection when the reduction from piercing exceeds their DEF or protection?

Yes.
There's various ways to reduce enemy protection: Lance Pierce, Bone Dragon, Spin Uppercut, and of course Brionac Σ(°Д°;

[Majimari]

Ah... ok. Well thanks for clearing that up for me.