You can only use 1 ""Infernoble Arms - Durendal"" effect per turn, and only once that turn
While red has very few nontargeted removal options to get rid of a Priest, black can run Diabolic Edict, Innocent Blood, and Chainer's Edict just fine
Why is that, I hear you ask
You can also use it as a way to reuse card effects that happen when a card is played by bouncing the Pokemon, then playing it again for the effect
In terms of its effect, untapping all of your Merfolk at the end of your turn is a fairly amazing static trigger, as it allows you to have some fun with Kumena, Tyrant of OrazcaKumena, Tyrant of Orazca or just generally showcase an impressive defensive roster of beefed-up Merfolk
But for more detailed overview of the most expensive Innistrad: Midnight Hunt cards, check out the rest of this guide