Do ToHit Debuffs stack with softcapped defenses?

While this is true, especially with softcapped defenses, you CAN use tohit debuffs as fake -def debuff resistance. If you debuff their tohit higher then they debuff your def, then you maintain your softcapped defense even when your below 45% def.

It may sound a little confusing, but it also works on tip missions DE (who have higher then a 50% base chance to hit you) and Lord recluse (who may resistance the tohit debuffs, but they still have some of an effect on him)

The former, yes. The latter... A +4 AV resists 85% of your debuffs. I've seen numbers around 45% to-hit debuffing for a */DM/Soul with DN up, but against LR that's a paltry 6.75% to-hit debuff - more like an extra Combat Jumping than the full softcap itprovides against +0 minions. Considering LR comes with a +30% to-hit buff from the blue tower...

My understanding of this:

To-hit debuff and +defense are effectively interchangeable. This is a poorly understood strength of Willpower: RttC should always include debuff slotting in defense-oriented builds.

Adding defense to your build affects only you, and you can be debuffed.

Adding -to-hit debuff to your build affects everyone in your team, as the things debuffed are debuffed vs all, but to-hit debuffs tend to be resisted quite a bit more.

It's all balanced, you see.

I disagree with slotting RttC for the debuff.

RttC provides 3.5% to hit debuff base. Adding a slot for the debuff grants you 0.9% extra debuff. Against even cons.

Against +2 enemies I am looking at 2.8% base vs. 3.5%, which means the slot was worth 0.7% extra debuff.

I think the slot(s) can be used better somewhere else in the build.