The breaking

At 16 in the kingdom of the Moon, to graduate from school you must endure a grueling trial that weeds out the weak from within their population.  This trial is determined by your moon.
1st moon: You are strapped to a post in a small prison underground and whipped.  You are left down there chained for three days.  You have enough room to stand, but if you crouch, or sit, your arms will be raised as the chains are short. You get no food and no water.  Rats are let in and will want to get at your open wounds.  You must survive, maintaining the strength to beat back the rats is key.  Many participants are found dead and half-eaten by day 3.
2nd moon:  you are chained, weighted, and gagged using magic. You are driven out to the middle of a lake, and thrown in. You must escape the chains as you sink to the bottom of this lake it is bitter cold, and there are dangerous creatures lurking within. it will be a 4-6 hour swim to shore. You are unable to use your verbal magic.
3rd moon:  Recieve your second soul.  children of the 3rd moon are often sickly and at 16 are old enough to survive the procedure that will heal them of dimension sickness. A second person, often a flare will be brought in, and their soul will be torn from their body using a Reper.  They are tethered to your soul.  A painful transformation, but one that doubles the power of the receiver, while leaving them haunted by the ghost of the second soul.