(XX% Chance of) YY(%) Reduced Target's Resistances

I understand most of the advanced game mechanics regarding resistance reductions, types of things that are only applied when weapon damage% is used, and procs, but this particular mechanic still confuses me a bit.

Mindwarp and Essence of Ch’thon, for example, have a chance to reduce a target’s resistances by a percentage, and “Of the Wastes” suffix adds a chance to reduce them by a flat amount.

Let’s say that I applied Essence of Ch’thon to a dagger of the Wastes. When would those chances to reduce targets’ resistances proc? Would it only happen when using skills with some weapon damage, or any time I deal any damage? If it is the former, would the value then be multiplied by the weapon damage%? In other words, with a chance of 28 flat resistance reduction, would a 50% weapon damage ability apply 14 or the full 28? Taking that one step further, would a higher WD skill (Cadence, for example) increase the amount of reduction applied (that could end up well over 100 at full overcap, so I don’t think so)?

Basically, I’m currently working on a build that has a few different sources of “-XX% resist” but no “reduced” resist, either flat or percentage. Would a weapon with that suffix/augment be a good source of said reduction, or would it not proc often enough on my intended target to be effective?

Also, I understand that XX% Reduced target’s Resistances would not stack with YY% Reduced target’s Resistances, as it would simply pick the higher of the two, but how would Corpse Desecrator’s ~20% Reduced target’s Resistances interact with Temporal Tempest’s 20% Reduced target’s Elemental Resistances? Since they’re not the same type, would they both apply, or would only the Corpse Desecrator be applied since it reduces all resistances, and Elemental Resistances is simply a subset of that? Elemental Storm from Rhowan’s Crown constellation and a Master’s Spellblade is another example using flat resistance reduction that I’m curious about (although the answer is probably the same as to the previous question).

-Works through sources of % Weapon Damage
-Is modified by % Weapon Damage
-Cannot operate at higher than 100% efficiency (500% Weapon Damage = 100% Weapon Damage for the sake or RR)

Sounds like a plan.

What about the last part? Another, less wordy example would be Acid Spray (Manticore constellation) and Elemental Storm (Rhowan’s Crown constellation).

I’m well-versed enough in the different types of resistance reduction to know that flat reduction won’t stack with another source of flat reduction, but the note in that image ("Different types of reduction can be applied, but only the highest for each damage type will be applied) isn’t as straightforward. Does that mean that Acid Spray’s “25 Reduced target’s Resistances” and Elemental Storm’s “30 Reduced target’s Elemental Resistances” are different types, and will stack for elemental? Or does it mean that the highest of each type will be selected, so enemies I debuff will receive 30 reduced elemental resistances and 25 to everything else?

This is correct.

Correct. 30 to elemental and 25 to all other.

Okay, thanks. I suppose any other way would be a little too overpowered.