guardians of light needed to be gathered, the 13 darknesses were almost gathered, Sora lost all his power due to what Xehanort did to him wiping him clean to be a vessel. Sora needed to learn the power of waking to save the BBS group and Roxas, Xehanort was playing chess while everyone else was playing checkers. He killed them but, due to Sora using the power of waking incorrectly he managed to save them and also going back in time before they were murdered. Things play out differently and then they fight the 13 and the 7 clash which the 12 died and Kairi makes the X-blade, Sora battles Xehanort he dies again but uses the power of waking and manages to get the Win. Due to using the power of waking so much "His heart ends up breaking" as Xigbar says. He uses it to save Kairi and ends up saving her then vanishes due to ot the power of waking. That's pretty much a summed-up version of what happened.
guardians of light needed to be gathered, the 13 darknesses were almost gathered, Sora lost all his
