Ougon no Keikenchi

The long-awaited launch day for the VRMMORPG Boot Hour, Shoot Curse has finally arrived! As a dedicated VR gamer, Leah eagerly rolls up her character, excited to make her mark on the grand tapestry of this virtual world. A chance encounter at the start of the game leads Leah to a fateful discovery: a hidden skill called Retainer allows her to tame any NPC in the game and pool their experience points with her own! Combining Retainer with her powerful enchantment spells, Leah steadily builds an army of retainers made up of formidable unique boss NPCs from the game. With the experience points pouring in, Leah establishes herself as a force to be reckoned with...only to be branded a living natural disaster! Well, if the NPCs want to crown her Queen of Destruction, who is Leah to argue? Opportunities to speedrun the destruction of humanity don’t come around very often, and Leah has no intention of letting this chance go to waste!

[From J-Novel Club]