Can the Intimidate skill be used to debuff during combat? If so, it could be both at-will and nonmagical, and benefit from Cha.my own take on the Bard class turns it into an at-will dedicated de-buff class, that's only available for multi-classing.
a dedicated de-buff class couldn't actually contribute toward the goal of combat, so making sure they're also a Wizard or Fighter or something means they can still deal damage when the Bard gimmick starts to wear thin.
The Intimidate skill has its own difficulties. Recently, I switched the key abilities as follows.
- Str (Intimidate) - strictly physical intimidation.
- Int (Deception) - that can survive scrutiny
- Cha (Persuasion) - psychological charm, frighten, and reconciliation.
I am happy with this skill threesome. In this context, Persuasion can influence morale, thus be used both to buff and to debuff during combat.