Counter-Spell: Target a player and select an ability (all Unseen, Cult and Neutral Killer abilities are listed). If target is of the evil faction or the Neutral Killer and attempts to use the ability you selected, your Magic Barrier will grant death immunity.
Divination: Predict who dies next. If you are correct and the player was not Blue Dragon, your next use of Magic Barrier will grant death immunity.
Nature Bender: Target a player and select an element to infuse them with. Fire will kill their visitors, Water will heal their visitors, Earth will prevent their visitors, and Air will be the same as current Magic Barrier (this ability would replace Magic Barrier).
The following abilities might be variations on ideas that have already been proposed:
Wall of Ice: Select two players. Only the second player will be able to visit the first; all other visitors will be prevented.
Empower Spell: Empower a player’s ability. Killer/Offensive abilities will bypass immunities. Investigative abilities will provide more precise feedback and not be fooled by frames or the Mastermind’s passive (Princess flirt will give exact class, Observer follow will identify visits that aren’t technically visits). Heal will heal Reap and Frenzy. I can’t think of a way to empower social abilities.
Perhaps Empower, if misused on Mastermind/Cult Leader, could allow them to convert Alchemist, Fool and Scorned.
Magic Barrier 2.0: Super-duper empower a player, making them immune to all negative effects and also allowing their abilities to bypass all of their target’s immunities. So a Knight could kill a death immune Sorcerer, but if misused on the Mastermind it would allow him to convert Prince