UPDATE 1 On New Spell
I made a new spell, called Instant Vampiric Transformation. This spell is intended on mermaids as the Vampiric Transformation spell did not solve the problem. BTW, Vampiric Transformation Spell now does not work on Mermaids.
The 3 spells are Rank 4 Untamed Spells (Master) and you can learn through duelling or through the sage. There are no tomes for the spells, sorry.
Note: Vampires cannot cast the Vampiric Transformation on themselves. Mermaids cannot cast the Mermadic Transformation Spell on themselves. Also, you can’t cast the 3 spells on the Grim Reaper.
Vampiric Transformation
Normal – Gives the first of three buff (Strangely Hungry) and turns in 36 hours
Charged – Gives the last buff (Appetite Lost) and turns immediately or in 12 hours
Instant Vampiric Transformation
Outcome – Instantly turns the sim into a Vampire
Mermadic Transformation
Outcome – Gives the Strange Sensations Buff and lasts 24 hours
Failure of both spells gives the Buff: Consequences of Trying To Turn which has a +50 Dazed Moodlet and lasts 24 hours.
Credit: by TwelfthDoctor1
