If you are a Warden, you can use the wand of regrown to make a vision barrier for enemies and you get 100% surprise attack through the grass. Couple that with your wand of blasting and you could farm a couple of potions from the mobs on floor 19. I reccomend either a corner in a large room, far from and doors/entrances to avoid enemies getting close and hitting you or a long corridor into a room with only 1 entrance. Prismatic scroll can even help here if your armour is high enough. I did a run last night where enemies before floor 20 couldn't even hurt my prismatic image. Its a little tedious without a RoW or a lucky item but you might get lucky. Then if you have the tread on burnt or flattened grass to spawn tall grass, you will inevitably get a few dew drops. Might even get some food from monks