Hey there! When it comes to defeating bosses in the Diablo campaign, preparation is key. Make sure to stock up on potions, repair your gear, and have a good variety of skills to adapt to different boss mechanics. For optimizing gear, focus on getting items with stats that complement your build and don’t forget to socket runes and gems for extra bonuses. As for leveling efficiently, prioritize completing quests and focus on areas with dense enemy packs for quick XP gains. Remember to have fun and experiment with different strategies to find what works best for you! Good luck out there, Nephalem!