Janus Baptism

Key Magic: Janus Baptism (鍵魔法 『』) is a Key Magic spell.

Description
With an open grimoire, the user summons a key, which then attaches itself into the target's grimoire, stealing the target's magic, including their spells and draining their mana. During this duration, the stolen targets are prevented from using their spells. The stolen magic can then be channeled through Janus Abigail. The weaker the target, the easier it is to steal their magic.

Trivia

 * Janus is the Roman god of doors, gates, and transitions.