This build made getting masters at Moddok Crevice with two players and a bunch of heroes following us fairly easy. It allowed me to cripple the first runner (calling the target) and then, while the rest of the party killed it, to cripple the second.

Skills
Apply Poison (Wilderness Survival)
Pin down (Marksmanship)
Crossfire (Marksmanship)
Quickening Zephyr (Wilderness Survival)
Serpent's Quickness (Wilderness Survival)
Storm Chaser (Wilderness Survival)
Troll Unguent (Wilderness Survival)
Resurrection skill

Usage
Avoid using pindown until you reach the runners because of it's high energy cost and long recharge time. When you reach the runners, before approaching them, make sure one of them is highlighted (best if it's the one closest to you). Then, Apply Poison, Quickening Zephyr and Pindown (call your target as you attack) - as soon as you hit him, push tab - this highlights the other runner. Use Storm Chaser to run after him while Pindown recharges (if you have not used both Serpent's Quickness and Quickening Zephyr, the recharge time will be too long and you will lose the bonus) - use Pindown and call the new target.

Make your party aware of what you are doing. If you have a full party, ideally you are not the only one who can cripple. But this does work.

Attributes
Wilderness Survival 9 + 1
Marksmanship 12 + 1
Expertise 9 + 1

Equipment
A Recurve Bow or Long Bow with Crippling Bowstring is essential (the Long Bow may be on the slow side, but it has better range than a Recurve Bow).

If you have Crippling Shot, the above build is just stupid, it works but it's stupid. (At the time I came up with the build, I didn't have Crip Shot).