Lets just make something up on the fly, since I love this idea as well.
Bo - The Freljord Outcast
"_Bo was a troubled man, known as a thief in his home town. He spent his days looting from most who would dare walk passed him, even those less fortunate than him. Bo was cast out later, because blah blah blah. He wandered the Freljord believing at first it was unfair punishment. He was trying to make an honest living; He would think to himself. As time passed and the winter's embrace hardened Bo's survivability instincts, it also taught him what it was like to be humble for once. Truly, he sought redemption. Bo had heard a thief's legend about a magical item sought after, deep in the Freljord. It is said any who wield this weapon, may bring... i don't know, winter's eternal slumber or something. He walks up this mountain, finds this, what he believes to be a stick for helping him walk, it's
's old scepter. He finds out after training with the staff and upon his enlightenment, the branch opens to reveal the scepter Lissandra once had, with an ice spike at the end. This is the instrument he sought after all this time, in his hands this whole time. Bo, now enlightened, attempts to return to (insert city name here) to rebuild the failed man he once was, and serve the people of that city, so they will not have to endure the blistering winds in the Freljord any longer."
P: Every 3rd strike does bonus magic damage to enemies, reducing their armor.
Q: channel: Bo spins his bo staff on each of his sides, for x amount of time. Dealing damage to all enemy units hit. Enemy champions who have been in his duration of his Q for x amount of time, will be stunned if they do not move out of the way.
W: Bo extends the frost spike part of the staff outward, striking the first enemy unit hit. Dealing damage (AP/AD) Enemy champions hit are marked with "true ice" for x amount of time. Slowing them by x for x amount of time for x amount of stacks, stacking upto x times.
E: Bo extends his staff in front of him, creating a true ice frost shield from the frost spike in front of him, blocking projectiles. May recast this again to place the staff under you, and you may begin sliding around for increased movement speed.
R: Bo may slam his bo staff into the ground, rooting him in place. Recast this upto x amount of times to pulse an aoe frost spike circle around you, outward. dealing magic damage to all enemy units hit, and giving them a "true ice" stack for every spike theyre hit by.