Hey Greymark,
The Absorb spell (Dark Magic - I've noticed I've replicated the spell name for Matter magic and will need to edit/review this) is intended to be temporary for the encounter but appreciate I have not specified this.
The Life Drain was intended to be permanent but could be considered over-powered if someone 'spams' this so may need some balancing.
In general, I tend to run a 'low' magic setting so encountering mages is uncommon which mitigates some of these risks.
Again, thanks for the feedback I've marked up my play-copy with the feedback and will likely (at some point in the future) do a further review/sweep/edit of this minor errate.