Well, the first epic and all the others, you have to do two things:
1- fill up your mana enough for being able to "banish" the boss at least ONE time, i think the first boss costs about 7000 mana to banish.
2- Bosses are heavy armored, so get a strong purple gem, that reduces armor, and keep changing it when the boss gets off-range, so it hits him all the way, so the next time the boss respawn, it will take great damage, then you own him :)
Great game, but one bad thing:
you could put like an "inventory" of avaliable actions, like "team grow - 2 avaliable", because everytime you eat something, you need to re-check the hotkeys. 4/5!
haha Amazing game Man!! totally new kind of shooter, not only read misson - shoot - read - shoot, the story and gameplay are great, except for the boring part of read newspaper then "back, back, back". 5/5! :)