Board Thread:Questions and Answers/@comment-108.20.229.110-20141218173601/@comment-25179062-20141218181128

You need to complete Quests and Vortex events, so you can gain experience. When the experience bar (on the top left of the home screen) fills, your Summoner Level increases. Increasing your Summoner Level give you higher max energy, max unit cost, and max friends.