With merc Strength and my minimal CB damage from my gloves, this only took 30 mins
So here's the plan for Nightmare. I'm going to try not to leave A1 until my merc has an Obedience, which will mean a ridiculous amount of farming Countess and NM Pits for runes and chippies.
I'm also hoping to get a good bases for Harmony and Edge (bosses).