Coup De Grace character build?

[Chronocide]

finally noticed this one on my ability lists and started building characters around it. It's amazing and a very strong ability. I almost never used it in the Pen & Paper game, I think I was really missing out.

Let's see: stats to optimize
-full round action (don't think I can fix this one)
-Weapon melee range (lunge or reach weapon? Oh, perhaps size increase too)
-automatically critically hits (so crit range and hit bonus doesn't matter to hitting, but crit multiplier does)
-save or die is Fort (so con damage or other effects to lower fort saves could matter here)
>-Save is DC 10 + BAB + melee damage ability modifier + weapon crit modifier

Initial Conclusions:
so BAB matters, but hit bonuses such as weapon focus doesn't. In fact, character doesn't even need to be able to hit the enemy, not really, crit muliplier matters, the damage ability modifier matters, and the BAB matters, but not other things.

So, for example, a 1st lvl cleric with a tower shield and a heavy pick and a Str of 14. So DC is 10 (base) + 0 (BAB) + 2 (Str) + 4 (crit multiplier) = DC 16

And then you need methods to make the target helpless...
Helpless is:
Sleeping, paralyzed, or unconscious. And potentially others that are helpless without one of those...

Witch sleep hex is pretty good, but not everything can be put to sleep... Others?

hmm...

[mk11]

A lot more can be slept if you take a 1-level dip into Crossblooded Sorcerer and pick Undead and Serpentine bloodlines.