So i was just doing some missions at the Drop Site, and all of a sudden this big warning comes up on my screen: CAUTION! EPIC ENEMY APPROACHING! Then this thing comes up telling me the enemy will dissapear in 2 hours so i choose "Fight On". Then we go into this 2D fighter looking screen where i can choose to attack him for free, for money or for gold. Attacked him for money and won a unit. I know i've heard talk of bosses before but it's never happened. I'm level 57 and have been playing for a couple of months. How are these triggered? How many are there? Anyone have some info on them? Thanks!