Board Thread:Game Discussion/@comment-9204520-20130524201046/@comment-9099835-20130528152331

Which bosses you see when exploring is based on your current player rank at the event. The closer you are to the top spot, the stronger the bosses you see. For example, I am currently in the 2500-3000 range, and I pull starscreams 3-5 and megatrons 1-2 for now. If I was 2000-2500, I may pull only starscream 5 and megatrons 1-3 for example.

These shift down as the event progresses. In a few days, ranks 3000-4000 will see megatrons 1-3 and so on, then in another day 3-5 and so on.