OP-1 as effect on master track question

Hi musiclovers!

I’m creating a live setup with Ableton and mainly play guitar and vocals but I’m going to use some sparse rhythm tracks and a Vocoder to create more electronic vibe. I have a OP1 and have mainly used it as a sketchpad and for sampling, but I’d really like to mess with it live on the master track and to create transitions between songs.
So my question is, what would be the easiest way to do this? If I put the OP-1 last, then everything will go mono, which is not that cool with stereoeffects on my tracks…
But if that’s the only way to use it, is it better to have it in some kind of effectsloop or last, before PA system?

Your input is highly appreciated!

When I say mess with it live, I mean both to play some one-shot samples and to use the effects like Cow…

use it as a buss effect - send stuff to it, fx on full wet, fold back into your stereo out. don’t ruin your master mix through it, it’s not competent for stereo, noise, resolution.