This is the form Serona would take if she was to give the demon within her sword permission to take over her body.. for a limited time of course

a single swipe from her hand/claws could shatter every bone in a persons body

she would become about.. 10-13 feet tall (yeah.. i want her tall/big, or at least like a 'monster' sized lolz)
her body turns into a obsidian state which is hard.. but also a bit brittle. therefore if her body was to take major damage she would fracture with very sharp edges.

the inside of her body seems to be nothing but pure lava (which when she gets a 'crack' in her body, lava will slowly ooze out of her) her body temperature becomes 2,500 F. (more or less)

she is known to spew out lava from her mouth or chest (there is a large crack from her neck down to her lower stomach) at the victim which will quickly harden to become igneous rock to trap them.. also not to forget that as soon as the lava comes in contact with their body they would become overwhelmed by a boiling/burning sensation.

other than the information about not much else to say, but if anything else comes to mind the info will be updated to this.