Re: Most common "Flail" Dropping Monsters?
According to ATMA's drop calculator, the best places to find flails are in Normal Act 3's temples, durance, and sewers (everything in those places has the same chance)
Though I think you'd be better off making the runeword in a Knout (exceptional flail) if you can. The best places for those are the Nightmare Act 3 Swampy Pit and Flayer Dungeon.