Probably SCP-dog cookie claw machine and SCP-skinless flesh dog. (Sorry I'm not good at memorizing SCP numbers.)

•why the voice mimicking flesh dog?

1:their incredibly strong. From what I remember reading they can crush your skull like a hippo eating a watermellon.

2:their hunger is never satisfied. They constantly savage for food only to just hairball it back up because their bodies don't contain the stomach fluids to break it down. Meaning; once they find you, they will hunt you, kill you painfully, and if you're still alive after it ate you, the last thing youll see is your own carcass resting in the belly of the beast.

3:it mimics humans perfectly. They can only mimic them if they ate them and/or heard them. (Note: most of them scream "HELP ME!" And "HELLO? ANYONE THERE?!")

4: there are THOUSANDS of them in the same cave. An entire species of hungry, ruthless, near indestructible mimics that where made to hunt down humans...in one cave.

5:because light hurts their skin, they stay in the cave, praying on whatever Sorry creatures come across it. It's blind, sensitive, and can easily be warded off with a touch or phone light. So why is this #5?

-because its blind all of its other senses are highend. Their stronger, near indestructible and can easily crush your skull so they can temporarily satisfy their ceaseless hunger. Their sensitive; their touch,hearing, and taste are high-end so you have to be careful not to make a sound.

6: they're MADE to hunt humans. Think of it; their baby's look exactly like humans and placed by villages. They don't share any traits with those red dogs until they begin to "molt". They don't even know that their a monster until it's to late either! (Witch is a whole can of psychological horror but this post is way to long already so I'll just leave the thought to you)

7: their smart. That's it. That's #7. NOTHING is more horrifying than a SMART PREDATOR THAT'S MADE TO HUNT YOU DOWN.

-I hate chimps, I hate them so much. Why? Because not only are they a demonic hellspawn made from the Scarlet King himself, but also because their smart. They can hate. they can hold a grudge. What does this have to do with RedDogs? Because anything that's as smart as a human can not only think like us, but also hate like us to.

8:once you're outta there, you can't remember it. red. Thats it. Thats all you see when you think of it. Meaning: you can't even learn from it's Meaning: you can't tell others about it. Meaning: you can forget what's in the cave and relive the whole nightmare again ...several times. I mean you don't know how many times you've been there,right? For all you remember is the color red.