So, to answer your question, yes, it hopefully means modifier.
But this spell is actually kind of horribly written, since there is literally no reason to explain which ability score determines the spells save as the Spellcasting class feature does that for you. In fact, why even outline a separate save DC when you can simply state when the creature needs to make a will save, and explain in the saving throw section how the spell save works. As it stands, this spell is ridiculously more powerful than it should be from the fact that it increases with CL than with spell level, and therefore can be boosted via things like Spell Perfection and Varisian Tattoo, and doesn't follow the conventions of most other spells. Since it doesn't follow these conventions, feats like Spell Focus don't work with it, and neither does Heightened Spell, so that's really, really borked.
This spell should say in its save section Saving Throw , and therefore tying it back to your spellcasting DC. But it doesn't. Because for some reason the person who wrote it thought it needed an independent saving throw?
This spell is basically completely nonsensical and honestly could use a rework.