Battleborn

The most important factors in gaining exp are match time and completing challenges. The longer the match goes, the more exp you'll earn. Some challenges can be done every match/game, while others are accumulative. To view the list of challenges, view the Command tab.

You are likely to get this achievement before you complete all the lore challenges, but if you want to speed it up, you can purchase double exp boosters. There are 1, 2, and 5 day boosters. You have to use in game platinum which is purchased with real money.

The biggest gain in exp is earned for completing a characters set of lore challenges. You'll earn 500 for each character completed.