When I do Mount Olympus there is a bug that happens there. Sometimes when I battle Zeus or Ares they are not there but their minions. When I defeat the minions, I have to get into another battle then I can defeat the boss. This is really annoying, I would rather defeat the boss and his or her minions in one battle. It will be nice if KingsIsle fixed this. Thank you
To avoid this problem, and it happens often throughout the spiral, you need to run straight for the boss to get him/her to join the fight the first time. If you run into a minion first you run the chance of pulling the second minion in before the boss.
This is not a bug at all. You simply go up to the Minions, and when the battle starts, the boss does not get pulled in. Make sure when you are going to start a battle, you run into the boss.