2 freaking hours. 2 freaking hours trying to beat a story boss.

It's been awhile since I beat him as a healer (took me 4 tries I think, and a bit of coin on gear upgrades), so possibly the fight has changed, but my advice is:

1. Bring your tank pet (I used Iresso, Qyzen could work too, but Iresso is easier to gear with quality moddable weapons). Be sure they are equipped as a tank, with a shield, not a power generator. Be sure they are in a tanking stance, and their taunts are auto-enabled unless you are prepared to trigger them yourself.

2. Let your tank start combat, and focus on keeping him healed/bubbled. Remain just outside the room so you can break LoS on Stark easily.

3. Either use focus target and focus target modifier, or constantly change targets, to keep an eye on Stark. We didn't have target-of-target when I did this, so I would start casting a heal on Iresso and switch my target to Stark while the cast was still going to make sure he wasn't casting something I needed to interrupt.

4. Interrupt his channeled damage ability (Project Storm, I think) as quickly as possible. Even if you have to cancel your heal cast (by taking a step), interrupt it immediately.

5. Interrupt his heal AS LATE AS possible. If he spends 2 seconds casting a heal only to be interrupted, that is 2 seconds he is not causing any damage, while your tank continues to wear him down.

6. NO other abilities need to be interrupted. They should cause minor amounts of damage that can be healed through, if your tank is properly equipped/stanced/used.

7. At some point, he will probably force lift your companion. This is good, as it will heal your companion up nicely, but now you have face him. Force armor and DPS him down, interrupt as above. When your companion is fully healed, or you are just tired of one-on-one, break his LoS and he should switch back to your tank.

@ the OP...I wish I could be more helpful. But apparently, I also have the magic version (beat Stark with Nadia in one go, although I was 3 levels over him).

I know BW said they "corrected an issue that caused companion stat bonuses from equipped items to be miscalculated when the companion was resummoned," but I'm wondering if that may still be your problem (i.e., it isn't really fixed?). I was soloing the dailies a lot when I first turned 50, and I know some nights they were super easy, and other nights, there was a lot of spam healing--and it just didn't make sense to me.

Others in the thread have given lots of good ideas. I don't really recall my battle with Stark that well, but in general, I stay as far away from bosses as possible while still being able to interrupt (that way I stay out of any AoE's and such...although I'm not sure if Stark has one). I don't know if you use any stims, but a Presence stim might be good as it will increase your companion's DPS and help when healing your companion. Also, maybe try your Heroic Moment if you haven't previously?

I had a hard time ,too, and I did not know I could leave the instance and change companion, so I had to stick with Nadia.
I am a Balance Sage, and sure died a few times, but I tried something and it worked. I realised that the moment the battle starts Stark focuses on my companion and destroys her in a few blows, so what I did was collect aggro immediately by hitting him hard. I made sure to stand at the opening, between the walls to use LoS efficiently and used my interrupts on his heal and Project Storm. Force Armor, Heroic Moment and Unity (when it was still obtainable earlier on) did the trick.
I don't know if this could help a Seer, but for Balance it didn't go too bad. I'm happy he was a caster . Good luck, it sucks being stuck...

^^ this

I don't even know who Stark is, that's how easy I breezed through the entire Consular story. With no help. You should try Seer spec and just let Nadia go nuckin futs. That's what I did when I got her, and before her it was Iresso I had out dealing the pain.

I did this on a level 43 heal-spec sage. I heal and mostly level in PvP, so I just do the story quests to get companions and stuff.

I didn't know you could bring in another companion, I thought it had to be Nadia. She sucked of course, and died right away. After dying once, I realized I would need to think about this a bit. Here was my solution.

First, make Stark your "focus target," which you can do by targeting him and hitting alt+f. That is the default keybinding, and I suspect that's what you probably have. This enabled me to see his cast bar even while I was targeted on myself to heal. That way, if I was casting a heal and he was too, I would stop healing me to stop him from healing himself. Other than that, I led Nadia die again in the first 7 seconds of the fight, and just spent the rest of the fight going through the following cycle:

1 - cast dots on him
2 - run and hide behind crates
3 - heal myself while hiding
4 - interrupt his heal whenever he tries to do it
5 - repapply dots after they fall off

It wasn't easy, but I did get him on my second try. Someone in this thread could probably point out flaws in my strategy, but what I did worked for me. I'm sure it would work for you.

If you aren't someone who does a lot of PvP, then you may not be as comfortable or familiar with the "scurry and hide" method of playing a healy-sage, so it might take you a few tries to get the timing down, but this'll work.

I hope you get it though, no matter what strategy you use. I'm sure you will

I also did this with a heal-spec seer sage. Go get Theran.

1. He casts Holiday which is one of the best companion stuns you have
2. he heals you so you can concentrate on Stark or whomever
3 sometimes he gets the last shot. He did that today...for me...it was a headshot on the main boss that brought him down, after keeping me and my team healed while we all damaged, and keeping one person out of the fight with Holiday

The fight was nearly trivial after bringing Theran.

I've learned a thing... if you have to board another ship, or a station or whatever, Bring Theran. It's my rule and it's worked great.

There's a time and a place for every companion. Theran has Holiday and she's priceless.

force wave can be used as an interupt too

Hard fight this one, But as others said:

Use interrupts on his heals and you'll be ok.

OP, I noticed in your responses that you've failed to mention your level... If you're under-leveled, it's going to be very, very difficult. It's difficult enough for someone who's on-level.

I beat this guy on-level (with Nadia, even), but it took several tries. You've been given good advice here, for someone who's on-level. If it's still not working for you, I'd say you need to find a friend to help you. If you have difficulty finding someone to help, then ask more nicely, or come back when you're over-level and that'll make it much easier.

Seriously, you've been doing this for too long if you're really *that* frustrated.