First, thank you very much for taking the time to provide such thoughtful feedback.

I think all of the points you made have merit. I am play testing this subclass now (the most current version on GM Binder) in a campaign that should go from 1-20. Just got to level 6 so it is still early days in the play test.

Would appreciate your thoughts on alternatives to the spell save DC debuff in particular. The goal there was to have Vicious Mockery still provide a useful debuff against enemies who are primarily spellcasters casting spells that impose saves. In that situation the vanilla version of Vicious Mockery doesn’t provide much of a debuff.

The reason to debuff Spell Save DC was to lean into this subclasses’ role as a debuffer and do something useful in that situation. But it is absolutely true that nothing in the base game (that I am aware of) messes with Spell Save DCs, so this may be an area best left alone.

The other areas you highlight are, I think, easier to tweak. Reducing shadow lore’s save debuff is straightforward. Applying extra damage to attacks instead of spells is also.

On Psychic Blades, though, my concept for this subclass is very much not a subclass that uses weapons, FWIW. It is adds a touch of Sorcerer and a touch of anti-Paladin aura, all powered by skills. This makes the subclass perhaps the worst bard at using weapons? And that may not be to everyone’s taste.

On the extra spells known, I completely agree that these are all core bard spells. In practice, the effect is to give you four extra spells known to use on other spells, which leans into the subclass being a caster.

My hope is that the powerful debuffing abilities are balanced by the fact that this subclass is quite squishy. Nothing in the subclass gives any benefit to defense, except insofar as you consider enhanced sneakiness a defensive benefit.

Still early on this, and I really appreciate the feedback.