More than a dozen mages are getting reworks, ranging from large-scale changes to characters like Zyra and Brand to smaller but significant shifts for Xerath and Ziggs.Dragon spawns are changing to include a new set of elemental dragons, replaced 35 minutes in by an Elder Dragon that offers big rewards for taking him down. Combine that with the changes to existing magical items, and players can expect to wind up with a very different game in the wake of the mid-season shifts.
League of Legends have never stopped being relevant to the game, but over time they have suffered from a lack of mechanical identity. They just haven’t kept up with the pace of the game, and some of them are looking just a bit dated in light of more recent character designs and redesigns. So as the mid-season period hits the game, the mages are taking center stage along with magical items and elemental dragons.
Source: Official Site