This fits into the YBIYBI board because you'll have to convince your DM to let you use the original printing of Sword and Fist to let you acquire the Bladed Gauntlets that had a 17-20 critical range.
17-20 is already pretty good, what with the 20% chance and all. Improved Critical will bring this up to a 40% chance. Even better. Now, what if I told you that you can double that again? An 80% chance is ridiculous, but possible. All you need is the spell Hero's Blade, a level 9 spell from the ECS. It doubles your critical range, explicitly stacking with Improved Critical. 5-20 isn't too bad of a critical range, and the spell adds damage to boot. If your DM is even more of a lunatic, he might let you get a magical item with Hero's Blade as a constant/charged effect. Even without that, it's a fairly good Deathless spell with all the other bonuses it gives.
Throw in a few critical-activated abilities, maybe some kaorti resin, and hey presto you have a critical monkey.