I would basically transform into a being of magical energy but this energy could take the form of purple fire, rainbow electricity and/or Multicolored smoke with Star like particles of crystal dust radiating magical light energy.
This entity would be a genie/djinn.
But while we’re on the topic of humanoids, humans evolved from primates such as Simians, Do you think primates such as apes or monkeys Have a relatively semi-humanoid physique?