I came up with this strategy for the Ambitious Imp, after wasting all my potions one too many times looking for him.
If he's in a room with grass, or on a trap, or in a pool of water, he's extremely hard to find at times.. PLUS it's super frustrating for him to ask you to kill 8 monks, after you already killed 10 trying to find him; and you're running low on healing potions.
Here it is:
You need 2 Mind Vision potions and 1-2 Magic Mapping Scrolls
1.) If you have 2 scrolls, use the 1st on depth 17 and go straight to the exit - avoid all fights if possible.
2.) When you're next to the exit, use the 1st Mind Vision potion and zoom out, so you can see if the imp is on depth 17.
3.) If not, go down the stairs immediately, while the potion is still active, and see if he's on 18.
4.) If not, go directly to the exit (almost always on the opposite side of the depth entrance).
5.) When you get to 19, use Mapping Scroll and Mind Vision potion, and take most direct route to Imp.
Now you have not wasted all of your Healing potions, food, your time, AND you haven't killed all the Monks/Golems you need to kill to complete the quest.
All it cost was 2 Mind Vision potions, which I never use (and 1-2 Mapping Scrolls); a much better bargain than 6 Healing potions and 6 food you might go through, if he's on 19 and he's hiding in a pool of red water.
I don't bother. It neuters me hard not to, but I think wasting time and being ganged\mobbed by **CKING OP BULL**** monks knocking the weapon out of my hands all the time would make me die *AND* furious. Net win is not doing the quest.