Can you reduce your save DCs to have enemies succeed easier?

[Myradale13]

Strange question I know.
But I was just wondering about using shadow conjuration greater to create a bridge by mimicking wall of stone. It's instantaneous and effectively permanent.
My character can auto-fail his save and walk over it with ease.
But can I voluntarily forgo my spell focus, cha bonus and the like to make the save really easy? If the army of orcs following me make their saves, 40% of them won't be affected by the bridge and won't be supported?

[ErrantPursuit]

There might be some abilities which use the language "May increase the DC" or "Allowed" or "Can" but all the ones I can think of instead say "Increases the DC" meaning it's always on. Sorry, but you'll just have to dismiss or dispel your effects if you don't want people making the requisite saving throws. Possibly, you could buff your enemies, or hang up a sign that says "This is an illusion!" giving them a re-roll and +4 bonus.

[Myradale13]

Yeah, that's unfortunately what I thought.
Might have to research a new spell that allows it, and prevents the 60% real portion as well.

[ryric]

It's probably not strict RAW, but I'd allow a caster to dump their save DC down to that of a wand or scroll:10+level+min stat bonus. So greater shadow conjuration could have a minimum DC of 20.

Or, if you have Scribe Scroll, just make scrolls of the spell and it's automatically at the lowest DC possible.