"If you seek great power, go to the bottom of the dungeon east of here"
How to Complete
The bottom means floor 10. Waypoints every 3 floors will make it easier to get there through the powerful monsters.
On the spot you'll meet a not very talkative fellow named Mathias with 3 Dreadnought (boasting a merry level 128 with over 18000 hitpoints) already waiting to give you a hard welcome. Good news - they don't have that annoying "Immune" ability, so your honed sleep, paralysis and stun-using monsters will find their ultimate use. Fun fact - Death Sentence works too if you have an Archdemon or Thought to use it and some luck for them to survive until it times out.
Dreadnought recipe for defeating Mathias
Square topaz gem (with 100 attack) upon turning the quest in for a reward