The Frost Gate (mission)

This mission can be easily solo'd with henchmen. The bonus however is probably too hard (see below).

Primary
Destroy the Catapults, open the gate The catapults are easy to find since destroying each opens a gate which allows you to travel further south. You then have to clear an area and put a "gear" into 3 winches which together open the frost gate and complete the mission. Not mentioned is that you need to put the "gear" into another mechanism first to get to the area with the 3 winches.

It seems no matter how fast you do this last part of the mission a certain person gets killed.

Bonus
Find and return the Plans to the Dwarf This is a tough one since the plans are guarded by some tough mobs who cross heal and cast "shielding hands" or some other serious damage reduction spell. You need to do a lot of continuous area-effect damage to them, or use a mesmer or something to get them down. Whatever you do, make sure you pull them a LONG way from where they are roaming before starting to kill them. That way at least you can resurrect after they wander back and avoid a wipe-out.

The way to this guarded area is rather narrow and is just where you get the cut-scene where you talk to Rurik. Look for a catapult lever over in the west.

To complete the bonus you fire the catapult, and look for a newly opened area caused by its damage. Best to talk to the dwarf (who is located back in the ice cave) for the first time after this since otherwise he will follow you and probably get killed and then you can't give the plans back to him.