Booster Leveling Package Download Booster Leveling Package! Booster seamlessly adapts to your unique situation, allowing you to use any and all XP buffs. Works with Heirloom Gear. Works with Recruit-A-Friend. Works with Essence of WinterGrasp. Booster practically sets itself up. Our auto- downloader and updater will install the addon and keep it updated for you. Installing Booster literally takes maybe 2 clicks, with either Windows or Macintosh!