I've got a team of 5 Archers at lvl 55 (Hero, Deru, Taar, Aramen, and that BA chick from BW). I found a good strategy without any tanks or healers and am kicking A$$ in veteran.
The key is to use the knockback weapon enhancement for my entire party. You may think that I take a drop in damage for not using a Mark or Manashot enhancement, but actually I do much more with because I get the additional 50% damage from shockwave at ALL TIMES. Shockwave adds a FAT amount of damage and damages all monsters in a area. Add a good level of penatrate to that and you can easily double or triple your damage in a good monster stack.
To top it off, none of the monster get to reach you so there is no need for a healer or tank. This works against ranged units and enemy mages too because with farshot you outrange them all and the knockback also stuns them for about 1/2 a sec. With the fast fire rates of a bows, you can keep 3-4 enemies locked down at the same time.
Use lvl 3 thunderous shot to thin out heavy masses and to stun/take out mage packs. The knockback lock works wonders against pretty much all mini bosses. Use thundershots to take out minions and them pin the boss against a wall without taking a single hit.
Additional advice: Since knockback keeps your entire party safe, focus on maxing damage with nature aura and equipement. You can pretty much ignore armor and resistance and just pump dex and +damage items. Once you get the markman receipe ring, get 4x for every character to boost your shockwave + farshot (reagents are cheap - shop around).
Deru has points in nature magic for the freezing buff and Taar has points in nature magic for the the critical strike buff (bear).
To answer your question, I simply stood on top and shoot the boss with from the ramp. All crawlers that come up has to climb up the stairs, where they get cut up by the 5 bows and an occasional thundershot. The surgeon can't come up and his attacks can't reach me while my farshot arrows hit him everytime. To speed things up, I use my lvl 3 charged shots for about 3 of my characters, saving 2 for thundershots against the occasional crawler that makes it up. I took him out without even taking damage (maybe 1 hit from a crawler)
[This message has been edited by Ranger Team (edited 10-24-2006 @ 09:29 AM).]