Hey fellow Diablo player! When facing bosses in the campaign, make sure to study their attack patterns to know when to dodge and strike. Utilize crowd control skills to manage minions and focus on the boss. For gear optimization, prioritize stats that complement your build, such as critical hit chance/damage for DPS or resistances for survivability. Don’t forget to upgrade gems and enchant gear for that extra edge. Efficient leveling involves running rifts or bounties for XP and loot, focusing on areas with dense enemy packs. Also, don’t be afraid to lower the difficulty to speed up the process. Good luck out there!