If a monster is already available to summon from the banished zone, you can also choose a monster to banish from your hand and special summon it from banished zone.
Banishes from hand for cost
Special Summons from your Banished Zone / Sets from your Banished Zone / Special Summons face-down
Before this card comes out and people start calling it bugged, remember that yes, you CAN summon the same monster you banished, but only if you already have a monster banished that can be summoned this way.
Anyway, looks kinda cool for Necrofear decks that use big fiends like Invader and Empress. And maybe for BLS - Sacred Soldier decks too. It's probably best to activate it during the opponent's end phase to be able to immediately flip summon them next turn.