Getting high enough DPS to get through the map on Ruthless took me a while, had to farm some of the new patch pets.  All toons need max resistence and good health/dmg stats.  This map on Ruthless is no joke.  Right now I use 1 AFK Summoner (with cat and DPS pet), and 1 DPS Monk.

With the DPS Monk I take the lead and build slow auras and strength-drain aruas along the route as often as they fit.  If your pets are elemental, try to mix-match elements to counter mob resistences.  The strength-drain auras help with this as well. 

Harbrengers (spelling???) are freaking cheaters, stay distance from them if possible.  I have not lost to anything else, but if you get double teamed by Harbagers, you drop super fast, especially true on the last wave up to the build spot, so be aware.

Once you get to the end, the build isn't bad,  Build as far into the Sout-West Corner as possible.  Not much different from Theoran's build, but I do like a little wall of minions to keep the ogres off my stuff. 

Party on Build: Tower Boost Monk, 2 Summoners with huntress/monk pets, 1 Adept Upper

Loot rolls pretty good, and you get 2 eggs per player (same as Nightmare), so 8 total if you run 4 toons.  UPDATE: with the new-new patch they grant double accessory loot at the end too, which is very nice.

Good luck!