It wasn't a hard decision to reach. It was hardly even a decision at all. Marcia wasn't one to wait out something like this. She didn't know what the amulet would do under these circumstances, she didn't know what the banshee intended. Only one of those she had any control over, so she held up the amulet and spoke the command.
"By the wrath of the gods I banish you from this world. May no one suffer from the memory of your deeds," the words were clear, if lacking in the desired force, but they were enough to cause the amulet to glow and heat intensely.
Despite her best efforts, her hand instinctively releases its' grip on the amulet and it clattered to the ground. From there a beam shot out and enveloped the banshee. As the creature was sucked towards the amulet it releases Marcia's hand.
The girl dives to grab the amulet before the spell is complete, so she won't...uh. Marcia picks up the old plain necklace and tries to remember why she was in such a hurry to get it. It's not very shiny or pretty and no one else is here, so she couldn't have been in too big a rush.
A stinging sensation drew her to the much more important matter of the rug burns she had gotten on both of her knees from the effort. Dropping the necklace, Marcia pushes herself back to a sitting position and looks distressed at her injuries.
They weren't too bad but they stung a lot. Maybe she should get someone to help clean and bandage them. Was there anyone here though? She found herself a bit unsure on the details, but she'd definitely been all alone in these hallways for a long time.
She did remember locking herself in a room earlier. Why had she done that? Was she hiding from someone? Why was she even at this creepy old house again?