General

@skytheria: Your stance does damage and triggers DR, too.

Theres something else that triggers DR. Im quite sure Eye for an eye is not on here, and im quite sure i did not hit hilla during DR. Im facing the wrong way, and i did not hitokiri cause the CD is too long in CD mode. http://i.imgur.com/bTKMx2p.jpg

I can confirm Eye for a Eye triggers DR as its happened to me in normal hilla.

@vaseline: It's probably better to hear tips from a person who struggles with the Hilla stage, but I might have a few pointers to give (you can take them with a grain of salt).

As far as I'm aware, none of the attacks in dojo will 1HKO you. You can afford to let yourself get hit by Hilla's explosion attack if it means not putting yourself in the way of triggering her DR. Turn Quick Draw off the instant you notice the DR symbol.

Your other option is using Hitokiri Strike. This isn't at all optimal for clearing dojo in time, but it guarantees you'll make it past Hilla. I wouldn't use it the entire stage, but dabble it in enough times to still get a few hits from another skill in while preventing her from making big moves.

I'm under the assumption that you're running Rai Blade Flash for dojo. Hilla tends to move her hitbox upwards during some of her spellcasting, which forces you to jumpcast Rai Blade Flash to hit her. Shinsoku isn't a better choice for maximum damage, but it links quite nicely with Hitokiri Strike in a way that Rai Blade Flash doesn't, and has no problems hitting Hilla while she's in the air. If you want to try doing the tactic above, Shinsoku is a better pick for attacking.

Update: I did a run without it on the whole time, still died (lol) I'm suspecting its @repentant's 2nd assumption that keeps killings me, but I can't not be in melee range when she is in the middle of the map and the pentacle skill is occuring on the other side :'(

Just as a personal preference sort of thing, I never run Eye for an Eye in dojo. Unless you can get it to proc even a decent number of times (it almost never procs for me anywhere), it really doesn't help all that much. And yes, @repentant is right; they made the skill a toggle because it used to be passive and trigger DR. Now you can have it on if you want and it...still triggers DR. So yeah.

As a heads up, when you reach the Arkarium stage on floor 30, he also damage reflects.

It has never actually happened to me so I don't know for sure, but I'm going to assume yes. Damage reflect is most likely the reason why the whole toggle-on/toggle-off business exists in the first place. Whoever designed it should've made it so that the skill passive but unable to be reflected, but whatever.

Also make sure (if you're not doing so already) to dash out of melee range when she DRs, because Quick Draw's AoE damage can also get you killed.

I'm not sure, but it's the same for me. Doesn't seem to happen when I have eye for an eye off. So suspecting that as well I usually dont boss with it, cause its only 200% dmg. Meh.