Kalecgos is the first boss in Sunwell.
Stole this pic from bosskillers.com and added the red text. But the quality is craptastic:
You reach the boss from the bottom of the pic. Illustrated with my crappy painted arrow, with Lalecgos in the middle of the platform looking at you.
Whenever there is no char's alive on the platform the boss resets and disapear for about 30 seconds. When this happens the people from the demon get teleported to the platform. Then these people shall run to the area behind the boss (but not too far. There's a patrol if you go to far. Just stay outside the circle, but on the walkway).
From there you can res all the dead people you can reach. When you cant reach any more people, get a rogue to run in alone on the platform, get aggro and use vanish (also work with hunters and FD, and 1 person going in and suiciding). The boss will reset again and your ressers can run in and ress as many people as possible. Just be sure that NOONE is alive on the platform when the dragon spawns. If some people are there, then just stay there and die. If you pull the dragon outside the platform, then you have ****ED IT UP. And you will have to corpserun and reclear trash.
So whenever you see its a wipe, just have all your ressers enter a portal, and have them run to the right side when the dragon resets. You can keep doign this forever, as long as you have 1 resser in demon world, or a soulstone/CR/ankh/DI/whatever.
To sum it up:
1: When you wipe be sure to have 1 resser alive somehow
2: The resser run to the area behind the dragon
3: Resses everyone he can reach
4: Go FD/vanish/suicide and reset the boss
5: Res as many people during the reset as possible before the dragon respawn
6: Go try boss without having to reclear trash
Any questions?
Enjoy!