The angelic undead of Midnight Mass are some nightmarish beings, seemingly from heaven?
The spookiness of the wolves is somewhat hard to understand. There is really no visual difference to them, save for their very reflective eyes. It is in this subtle change that so much horror resides. They look just like us, and yet they aren't. They are the night-born reflections of us, and have a hidden hunger for those of the day. 9/10 spook.
The wolves are exceptionally dangerous, unable to die by normal means so long as they are continually drinking blood. However, they have one extreme weakness, that being their inability to live in sunlight. Much like that of vampires, they instantly combust on contact with sunlight, and because of this they cannot be the near the pinnacle of strength. 7/10 danger.
The transformation is not so simple. As I said, the only visual change to the undeath is the reflective eyes, however, the process to this point is not so simple. Ingesting the blood of the angel, that which gives these properties, corrects one's buildup. Paralysis is cured, age is reversed, wounds are healed, and because of that, the transform will be a 4.
Finally we have the name. Now it is hard to rank this one, and the name I decided to give them was the Wolves, spoken by a character near the end of the show. The line however is spoken as a metaphor, not as a direct name. Unfortunately then we will give them a 1.