The third item does not make the floor go down again. Use the Mirror.While your at it, PP Al-Adryian. He's got some uberstuff.
And if you stand directly on the stain, and apply the fluid below you (you can't in front of the stain) you can get inside the demoness (She manifests around your POV) You can also do this with Vi, the Shaman, Brekek, PeeWee, and most of the
Undead which appear when you touch corpses. It's very interesting. Panels you're actually behind are invisible, and you see a lot of parts edge-on as the objects move around you. How exactly centered you are determines what you see, and they look different depending on the direction and orientation of your excentricity.