Jayce, the newest character to grace League of Legends, is going to be the first character with multiple roles intended. His focus is around his transforming weapon with two different modes; The Mercury Hammer/Cannon. As the name implies, it is both a hammer and a cannon, meaning that you do not want to be on the receiving end of it.
The intention is to make a character who can fill the support roles of a ranged lane carrier as well as a tough opponent in close melee. Whilst in cannon-mode, he can buff allies and himself as well as create fields that will accelerate projectiles. His melee-mode on the other hand has AoE bursts and mana regen, along-side increased armour.
Jayce suits all kinds of roles, but I forsee him being used as a ranged hero who can move up to defend when lines are broken. The ability to adapt to the situation is always great, but where are they going to weaken him in order to compensate?
Will he have weakened armour or health? Maybe his damage output will require a lot of support. Versatility is great, but you need the strength to stay on the board as well as the power to eliminate your enemies.