For sound design and music that use space as part of the sound: moving it, bending it, darkening it, and painting new sound into it. None of these is a correction tool. They are the ones you open when you want a sound nobody has heard yet.
Bought one by one: €483. In Creative: €299. And the free ones, Encode, Downmix, View, Depth and Beacon, work with all of it.
Step up to Total: €600 more, for 23 more plugins. If you already own Creative, that is all it costs you — what you paid counts in full.