Rhassoul+water ! I use chamomile, but that's a totally personal choice, usually it's orange blossom that's suggested. Then i add a drop of lavender EO or lemon EO. I usually leave it on for 15 to 20 minutes.
There is also that recipe i tried when we were talking about that lush charcoal thingie. I use about 1/2 tbsp of rhassoul clay, then about 4 to 5 capsules of charcoal, a pinch of epsom salt, water and one drop of lemon EO. That makes enough for your face, and neck.
If you have oily hair or scalp, or just want a gentle shampoo, rhassoul is also fantastic for that, you need to leave it on for a few minutes (7-10 for me), massage it on the roots, then rinse, and wash the tub lol. You can also use it for your body, but i find it's too messy.