You gain the following benefits
Ability Score Improvement - Increase either your Intelligence, Wisdom, or Charisma by 1 to a maximum of 30
Mimicry - You gain the Magic Initiate Origin Feat Twice except you can pick the same class twice, you may also cast a second and third spell form one of those classes once per long rest
Sabotage - You get the Mage Slayer Feat and a +1 bonus to Spell Saves