Serial online fiction about teenagers training to be superheroes, required single combat

Question

I only remember a few details. Superpowers were a known thing in the setting, reasonably common. The kids are living together a suite or small building. There was a boy with super-strength who was prone to berserk states and a duplicator. All students were required to go into single combat against one of their classmates to begin training. The combat was in an artificial environment (a physical arena with prop buildings, not holograms) and was violent, sometimes deadly. In one combat, a girl who could teleport things close to her won by teleporting away the muscles of her opponent's legs. The berserk guy fought the duplicator and reduced most of the dupes to a bloody pulp after he lost himself. I'm pretty sure they also had a suspected shapeshifter fight.

I read this on a website in 2016 and it already had several chapters available. There might have been a physical book available for purchase too. I probably found the link off of TvTropes.org.

Answer 1

It is Citadel. Isaac Strong is the super-strong fellow. Hector Hive is the duplicator. The first combat has the teleporter bit:

The fallen strongwoman’s arms and legs were concealed by her black uniform, but they didn’t look right. They lay oddly, had the wrong dimensions. Four of what he’d assumed were fragments of the wall were actually bloody pieces of meat. The other girl struggled to get up on her working leg, then moved slowly closer. She stopped just outside of arm’s reach and said something, waited a moment, then seemed to repeat it. The fallen girl, SS, just looked up at her. White faced with pain, she eventually spat out a single syllable and the picture faded back to a plain stone wall.

....

Both learned valuable lessons. One, never to under estimate an opponent because she lacks obvious offensive powers. The other, that the ability to teleport small objects can be extremely dangerous when used to teleport only part of an object.

In the same chapter, Isaac's match with Hector:

Isaac came back with a startled gasp. He was kneeling on the ground. No, he was kneeling on Hector’s broken body, covered in blood and… other things. Looking around, he saw more like it. None of them were moving. “It’s over?” The doors were open. He stood up slowly. Nothing hurt but his throat.

Kelly Protean is the shapeshifter as detailed at the beginning of chapter 3.