Witch Gravewalker Archetype (from UM) synergizing aura of desecration

[Wolf Munroe]

So I'm making a gravewalker vampire villain and I was reading this ability:

Quote:

Aura of Desecration (Su): At first level, a gravewalker can create a 20-foot-radius aura of evil power. This aura increases the DC of channeled negative energy by +1 and the turn resistance of undead by +1. At 3rd level and every 2 levels thereafter, the radius of the aura increases by 5 feet, to a maximum of 70 feet at 20th level. This ability replaces the witch's 1st-level hex.

So, witches don't normally get channeled energy as a class feature. Is there an archetype or hex somewhere that I'm missing that will grant the witch the ability to channel negative energy, or is this benefit of the aura purely meant for allies?

[Javaed]

The Turn Resistance helps you out as you'll probably have a couple of Undead with you. The Negative Energy Channel DC boost helps out allies really, since it won't be worthwhile for you to multi-class two casters.

Now, if you can get an Undead Lord Cleric and an Antipaladin in your party, then you're in business.