"... Party house. I hear there are no landlines and there's no reception for them to call anyone. Let's go in and slaughter them one by one." You agreed and started your somewhat long walk. Going through the swamp and climbing up to the small wood pier you saw a lonely girl. It was a young looking elf in a woodland dress. She saw you and backed up and asked "Who are you? What are you doing here?" She was looking around, but no one inside noticed you as they were busy partying.
The mask said "No one's seen us. I think this is the perfect time to put on a disguise. First deal with her." You agreed with the last part and stumbled to the little one.
The little elf said "Oh you must be from that witch from across the lake... Maybe your a kind so-" she tried something odd with her magic as if she tried staring into your soul, and then she had the most terrified on her face as she squeaked out "BLACK!" You finished getting to her and grabbed her. The little girl tried to scream, but as you were crushing her small form she seemed to have a hard time getting air in or out of her lungs. You bit into her and started sucking and felt as if her essence was a bit more pure and potent than the witches. To be fair though the witch had far more essence.
The mask said "Alright now we get rid of that husk, but keep the clothes." You stripped the withered corpse and then tossed her far into the lake. "Now into a bush out of site. This disguise will be great." You went behind a bush and then the mask said "Ok, We'll use that girl's essence to temporarily change our body into hers."
You asked "Why? She's tiny and I can kill them all."
The mask corrected "No, You'd kill maybe 1 or 2 before they would start running. You could then kill many of them, but in the end several of them would get away and you'd become known for sure. If we disguised you and took care of them one by one, even if we let one go we'd become a myth and command more respect and even more people would come to us without proper precautions. Now let me handle this magic."
You said "Fine..." You felt the magic doing something to you and you shrank down rather small. You were nude before but looking at your body you noted that it was small, your skin was fair and blemish free, also undeveloped like the child you had just ate and female.
The mask said "I'm hidden through this magic, time for you to get dressed and then start cutting through the inhabitants." It took you a little while to get the dress on, although the panties were simple enough to get on. The mask then said "Alright, you've got a bite mark on your shoulder time to go inside and see if you can get sympathy from someone."
You thought and said "ok... time to put on my best act then..." and then as the little girl elf started to tear up and cry as you ran inside where...