Did it solo on my Nightstalker. Only died twice. Wish I would've switched to blade dancer for the Templar area just for invisibility. The first two spawns are fairly localized so cover was easy to find. That third spawn tho... Every time I got hit by a captain's bubble I'd spam jump all over til I could see something and then lob grenade and use inviso-smoke and get clear. My strategy ended up being to switch to sword, stalk the captains, go invis, wreck one, retreat to cover, repeat. After you get rid of them, it's just a matter of sweeping up the trash. The boss battle was sort of anticlimactic. There's more than enough room to pick your shots and clear ads. Just don't rocket yourself when he puts you in a bubble.