I hope you are playing intelligently with your HC monk. Vrkhyz can afford to test out builds in whatever MP level he wants since he isn't playing HC.
The more I think about this, the more I feel there's not much contest between the two runes, especially in HC. Let's look at what each one does.
- Backlash: Deals extra damage when mobs miss you.
- Hard Target: Mitigates damage when mobs hit you.
When it comes to keeping you alive, I think Hard Target is clearly the winner. Backlash uses a "MOAR DPS" approach to keep you alive. It's not a defensive skill at all
. It only offers you a bonus when you're not getting hit. About the only thing it has going for it is the extra LS, but that's relatively small compared to LS from your actual non-Backlash offense.
When is Backlash best? When you're surrounded by mobs. When does that happen? When you're surrounded by whites, when you run into Horde and/or Illusionist, or when you're taking a stroll across the Fields of Slaughter. The first situation doesn't matter because players rarely ever die to whites that aren't labeled "Fallen Maniac." In the second case, you're going to take a lot of incoming damage, which Hard Target will mitigate. In the third, well, FoS is just a really dangerous area, but it's also full of a lot of ranged mobs (Hellflyers and Impalers, with an honorable mention for Heralds) that won't clump together and improve your Backlash output.
So what does Backlash really bring? It helps you a lot against mobs you can beat without it. It gives you better LS against certain melee packs, but Hard Target has the added advantage of making your effective sustain much, much
more effective. How much better? Simple: In Demi's case, the extra armor increases his EL by nearly 13%, which means his effective sustain is also 13% better. Does he do 13% as much damage with Backlash as he does with his normal attacks? I haven't run the numbers, but color me skeptical. Against a typical pack, even with a few whites along for the ride, I'm thinking he won't.
I'm making this suggestion because I think Hard Target will help him stay alive better. I don't think there's much argument that it works very, very well, unless you think HC characters should routinely throw away 13% EL and eSustain in exchange for more situational DPS.