Per 
Hello! I am Polska and I have had an interest in writing SCPs for a long time.
Here are just concepts from either myself or my friends, these won't be the greatest SCPs ever written and might not be that much in detail since these are just concepts, not actual SCP Submissions.
Enjoy.
Item #: SCP-4273
Object Class: Keter
Special Containment Procedures: A Wall Built of a Chromium Steel Alloy, being about 100 m. high and covers ████ m. in diameter. Made far enough away that the Acid does not melt it even though after testing to find Chromium does not decay from the Acid, Personnel are advised to not ever go past it unless it's not in the Decaying Phase.
Description: SCP-4273 is the █████ region of Antarctica, during the months of November through February, a "Decaying" Phase starts. Anything in the vicinity of the region will be rapidly decayed by the Hydrochloric and Hydrofluoric combination mix of acid. Research of this Region has shown that anything during the "Decaying" Phase will be decayed or destroyed in hours of contact, when the phase ends, the acid seems to completely disappear with no trace of where it goes, Site-███-A has been built to research the acid and effects of contact with SCP-4273.
The Acid SCP-4273 emits is a combination of Hydrochloric and Hydrofluoric acids, melting Stainless Steel, Bones, and many other metals and most minerals. Bone will take about 30 minutes - 1 hour to dissolve by the acid, leaving nothing left except some gas that has escaped when the bones were opened, all research personnel must stay away from any samples of this acid no matter what amount it is as it is highly lethal and could dissolve their skin in seconds.
Anyone who looks at it directly has a 35 - 50% chance to go insane and start talking about [DATA EXPUNGED] as by Test-4273-1, where 5 D-Class Personnel were sent to the area and 2 went in, one was given a camera, and the other 2 watched casually.
History/Discovery: SCP-4273 was discovered when a group of Argentinian researchers and miners went out to the █████ region of Antarctica to research and mine into the snow during the month of January, 19██, the research and mining supervisors didn't go in to keep watch and inspect around the place, and what they saw, they would never forget.
They saw the skin of their friends just disappear like it was a ghost, they saw how the bone started to disintegrate and small amounts of visible gas appeared and disappeared as the bones were torn open, they made a beeline straight back to the research facility they were stationed at and told the others what they saw.
Soon the Foundation was called in to investigate and for sure when one of them went in they started to disintegrate from the acid, they built a 100 m. chromium steel alloy wall around SCP-4273 to contain it and to make sure it was secure, the chromium steel alloy was tested against the acid and it resisted it, MTF Lambda-4 ("Birdwatchers") must be called in if any experiments with SCP-4273 are done.
Addendum 4273-1: Senior Researcher ████ has requested D-Class Personnel, maximum of 5 D-Class Personnel, to experiment on the acid SCP-4273 secretes during the "Decaying" Phase. Pending 05 Approval.
Addendum 4273-2: 05 Approval of Senior Researcher ████'s request to experiment on the acid SCP-4273 has been accepted, 5 D-Class Personnel were sent to the █████ region at 19:04:34 with MTF Lambda-4 ("Birdwatchers") to keep watch of D-Class Personnel and check Site-███-A's capabilities.
Test-4273-1 - 14:52:03, 19██
Subjects: D-6345, D-9137, D-3485, D-7423, and D-████
Procedure: D-9137 and D-7423 were sent into SCP-4273's Containment Chamber and D-6345 was equipped with a video camera and extra fine binoculars refined by SCP-914 for the best view and D-9137 will walk into the area of acid to see how strong it is.
Results: D-9137 and D-7423 walked into the area and started to reduce into nothing, D-6345 recorded for 4 hours fully and watched as D-9137 slowly disintegrated into nothing by the acid, and D-7423 looking like the soul was leaving her body, both screaming loudly until their death by blood loss after both D-9137's legs disintegrated and D-7423's heart was pierced by the acid, D-6345 was then interviewed by Senior Researcher ████, D-3485 could not be interviewed due to him seemingly going insane shown by the footage at 2:13:54, where he suddenly starts fidgeting and shaking drastically, yelling, "They're in there! Kill the █████████ still alive, ██████████ of the █████ realm!" and [DATA EXPUNGED]. D-████ was interviewed as well, but a error in the audio and video recordings made it impossible to get anything information from it, and only Senior Researcher ████ knows.
Analysis: Due to what the acid does to the human body, it is decided that it is a combination of hydrochloric and hydrofluoric acid, all research personnel must use Chromium built materials and test tubes to handle the acid.
Interview-4273-1 - 18:42:14, 19██
Interviewee: D-6345
Interviewer: Senior Researcher ████
Foreword:
<Begin Log>
Senior Researcher ████: What happened when D-9137 and D-7423 went into the region..?D-6345: First, his skin started to fucking peel off, and her right arm just shriveled up!
Senior Researcher ████: Refer to not using strong language, but continue.
D-6345: I don't know how long I watched, but I watched as the flesh disappeared off their body, my brain was continually saying I was lucky I didn't have to go in there…
Senior Researcher ████: Interesting, did it dissolve the bone structure?
D-6345: Of fucking course it did! That look he gave me before entering, it was a face of disappointment in me for not volunteering to enter it… but she took it like a champ, but you could see… her heart! Pierced and cut into two, the other screaming about [DATA EXPUNGED]
Senior Researcher ████: Thank you for the information, you can go back to your cell.
<End Log>Closing Statement: D-6345 was then escorted to his cell and given Class-A Amnesics.
Item #: SCP-4306
Object Class: Keter
Special Containment Procedures: SCP-4306 is to be contained in Site-██, in a Bottom Floor of Heavy Containment, being a 5 x 5 x 5 meter box with an elevator which should always be up. If SCP-4306 is to escape, a Containment Breach will be called and normal procedures to re-contain it will start. The walls of the containment chamber will be reinforced steel with a thickness of ██, if there is any dent in any of the walls with a decently big size, repair must be issued.
Description: SCP-4306 is an entity that cannot be seen by the human eye, but can be seen with Night Vision Goggles, it is able to be communicated with, but no real interview has been issued yet. It communicates telepathically, reading the brain of the person and imitating the voice of a loved one in their head, which will try to lead them to go down into the containment chamber.
It will then swiftly slice into the neck of the victim, killing them almost instantly, anyone that is to be tested with SCP-4306 is to be informed of this so they don't let it breach containment. It can communicate normally with the person in their head if they know what it is capable of, use of this function for interviews has not been used. Any D-Class Personnel trying to let it breach containment will be terminated immediately, SCP-4306 has breached containment only 3 times.
When seen with Night Vision Goggles, many describe it as an "Invisible SCP-939" but with no red on it's skin and is a lot more humanoid, having no lower jaw or eyes, with a hole on both sides of the head to indicate it has ears, it can walk on 4 feet or on 2 feet. It is about 3.5 meters in length, and looks very healthy with half as much ribs as a normal human, but very skinny to see through the bones, with very sharp fingernails.
SCP-4306's fingernails can cut up to the thickness of ██, lower than the reinforced steel thickness of ██.
Addendum 4306-1: SCP-4306 has breached containment at 17:54:31, all on-site personnel should evacuate immediately.
SCP-4306 has been re-contained at 01:32:56 the next day, there are 2 MTF Casualties before the reinforcements and 11 Casualties after, with 6 Scientist Casualties, and 27 D-Class Personnel Casualties.
Addendum 4306-2: [DATA EXPUNGED BY 05 COUNCIL]
Addendum 4306-2-C: Casualties have been shown by 05 Council: 34 MTF Casualties before reinforcements and 21 after, 23 Scientist Casualties, and 68 D-Class Personnel Casualties.
Addendum 4306-3: SCP-4306 breached containment at 07:01:43, but quickly re-contained 2 hours later with no casualties after reinforcements arrived.
Addendum 4306-4: Site Director █████ has requested for a D-Class Personnel to conduct an interview with SCP-4306. Currently pending 05 approval.
Addendum 4306-5: 05 Approval of Site Director ████s request to have a D-Class Personnel conduct an interview with SCP-4306 is accepted.
Interviewee: SCP-4306
Interviewer: D-13846
Foreword: D-13846 was sent to stand in front of SCP-4306's chamber and was told before the effects, if D-13846 tries to go into the elevator they will be shot.
<Begin Log>
D-13846: Uh, Hello?SCP-4306: Yes, Hello ██████. Mind coming down the elevator in front of you?
D-13846: I know what you're capable of, cut the crap.
SCP-4306: Fine, what are you here for then?
D-13846: I am here to interview you, so if you could answer these questions to the best of your ability, that would be appreciated by my "higher-ups".
SCP-4036: You mean the people that make you their guinea pigs, lab rats, test subjects?
D-13846: Yes, but I can't do anything about it, so just answer the questions and we can both be left alone.
SCP-4306: Fine.
D-13846: Good, first question: What was it like before being captured?
SCP-4306: Well, I was just roaming the world, having fun killing the worthless human population in colleges and Restaurants. Then your people took me captive like i'm a damn prisoner.
D-13846: Okay, next question: Why are you invisible, and why do you look like what you do?
SCP-4306: I have always been invisible, a predator of the day and night. I look fine for my kind, is there a problem?
D-13846: There is no problem, and you mean there is multiple of you?
SCP-4306: Of course, hundreds and hundreds of us.
D-13846: Okay, moving on to the next question: Are you related to SCP-966, the "Sleep Killer"?
SCP-4306: Oh, 966 is a brother species, we are close, but different.
D-13846: Next question then: Why do you love killing?
SCP-4306: I love the fear and the screams the stupid people have when I slash their necks open and the blood spills onto the white floors, darkening them to a crimson pool.
D-13846: Um… Okay then, that's all they've given me.
<End Log>Closing Statement: D-13846 was escorted back to his cell and given Class-A Amnesics.
Item #: SCP-4352
Object Class: Euclid
Special Containment Procedures: SCP-4352 is to be contained inside a thick reinforced steel case being about 1.5 m. per wall with one being thick glass to see the object through the Observation Window.
Anyone entering it's chamber must wear a hazmat suit or hefty armor around the chest and stomach region. If someone enters without permission, they will be punished severely, entrance into its chamber requires Level 4 Access and only D-Class Personnel that have been requested are allowed in.
Description: SCP-4352 is a piece of thick Wagyu Steak, being about 1.5 m. in length and about 0.7 m. in height, when cut though, inside it is hundreds of small eyes. When the eyes make eye contact with the person, it proceeds to spring hundreds of spiked tentacles at the victim, completely immobilizing the person and proceeds to stab straight through the heart, stopping any life left instantly.
It cannot move physically, and won't attack unless the eyes make eye contact with someone, after the person has died, the eyes then disappear back into the steak and it starts to regenerate the skin that was cut off of it. If someone tries to further attack SCP-4352, it will regenerate rapidly, and then kill the person with a swift puncture into the heart, killing instantly as well.
Addendum-4352-1: Site Director █████ requested that 2 D-Class Personnel should be sent into SCP-4352's chamber. Pending 05 Approval.
Addendum-4352-2: 05 Approval accepted, 2 D-Class Personnel are sent into SCP-4352's chamber and are given a knife including a mirror to see what would happen if it made eye contact with itself.
At 14:34:52, D-8126 and D-9843 are sent into SCP-4352's chamber and the door is closed and the glass is lifted, D-8126 uses the knife given and cuts the steak in half and looks away after seeing the small eyes, but did not make eye contact with SCP-4352 yet.
D-9843 goes up to SCP-4352 and puts the mirror in front of the eyes and they make eye contact with themselves, but nothing happens, D-9843 tells the researcher it does not work and their work here is done.
The researcher tries to open the door, but it won't open due to a failsafe breaking during the locking of the door, finally D-8126 looks at SCP-4352 because she thought the mirror was still there and makes eye contact with the small eyes.
Hundreds of Tentacles with sharp ends shoot at D-8126 and multiple push into major blood vessels in the legs and arms, immobilizing D-8126 and then soon after hundreds of them push straight through in her chest, going completely through the heart and all functions of D-8126 cease.
D-9843 bangs on the door and yells to open the door while cursing out the researcher, the researcher finally fixes the failsafe and opens the door and looks to see D-9843 alive, but instead sees a tentacle puncturing through the front side of his body, he is clearly not alive and the researcher closes the door again.
He suggests no more tests should be done on SCP-4352.
Item #: SCP-4709
Object Class: Safe
Special Containment Procedures: SCP-4709 is to be contained in Site-19 in the same fashion as SCP-012, Personnel are allowed to see it and must see it immediately if happened to make contact with SCP-012.
Object is to be encased in a room on a small table with glass walls around SCP-4709, the front side of the glass case will have a handle to open and remove SCP-4709 in event of contact with SCP-012.
Description: SCP-013 SCP-082 SCP-4709 was discovered 14 m. away from SCP-012, first being labeled SCP-013, until it seemed it was a normal composition and SCP status was removed, it was given it back, but was then removed by Site Director after a Senior Researcher brought SCP-082 up to him and showed that it was normal.
It has been brought back up recently and shown that it reverses the mental effects of SCP-012, being very useful for tests and can even stop the urge to finish SCP-012, termination tests using SCP-012 can be used to show that it actually heals the victim that harmed themselves, and can bring them back to life if they have died in a 15 minute window.
Addendum-4709-1: Dr. ███████ has requested to test the regenerative abilities SCP-4709 has on humans, healing any wound caused by SCP-012 or even other SCPs. Pending 05 Approval.
Addendum-4709-2: 05 Approval Granted for Dr. ███████ to test the regenerative abilities of SCP-4709, D-17832 is sent into SCP-012's containment room, SCP-4709 is next to SCP-012.
D-17832 is instructed to sit in the chair in front of the compositions, he does so.
D-17832 starts to dig his fingernails into his wrist, but stops right before doing so after accidentally touching SCP-4709.
D-17832 then is told to try again, this time he digs his nails into his wrist, drawing blood.
D-17832 starts to heavily bleed while writing the composition in blood, but then instructed to place his hand on SCP-4709.
D-17832 does, and it completely heals his wrist and cleans the blood off his hands, this seems enough for Dr. ███████ and he tells D-17832 to exit the containment chamber, he does so.
D-17832 is then escorted by guards to his cell and given Class-A Amnesics.
