The Kingdom of Kaliron

i have been playing TKoK the last few days with 2 friends with a warrior / paladin / arcanist setup and we completed everything on legendary but the quest "the beginning of the end". you have to put an end to the demonic onslaught or something...
how can we beat this quest? do we have to push forward 3 versus over 9000 demons or is there another way?
also, you can start the quest multiple times, with more and more mobs spawning. your pc will love it (at least mine does ;> )

The main way people do it is just pushing through the demons to kill the gate. It is ideal to have 2 arcs and 2 healers but it is definitely doable with that setup. Another way you could do it and actually the first way I succeeded is by buying a bunch of troops and running and hiding along the side and waiting for a wave to pass which will be 5 groups. Then you go till you get kill a gate. TP back to clear the town and repeat.