Its ultimate ability lets you place a vampire card onto the battlefield without paying its mana cost
This card, Disturbed Slumber, would benefit a green deck that focuses on aggressive strategies and creature-based tactics
While you do need to jump through hoops to make your opponents lose life, simply saving your big plays for after combat in the second main phase could allow you to cascade off of some of the deck's bigger cards and hit some spicy bombs
718.3: As a player casts a prototype card, the player chooses whether they cast the card normally or cast it as a prototyped spell using the prototype keyword ability (see rule 702.160, Prototype)
That includes stuff like Master Transmuter, Scarecrone, and Kuldotha Forgemaster
If tails, the attack doesnt happen, and you put 3 damage counters on your Confused Pokmon