Ultra Rapid Fire, the game mode originally thought to be an April Fools joke, has been temporarily released! Featuring 80% cdr on all spells and activatable items, no mana costs, increased movement speed and gold gain, and DOUBLE attack speed on ranged champions, this mode is sure to beef up your reaction speed.
Popular champions on this mode that I recommend are: Zed, Orianna, Nidalee, Alistar, Hecarim, Sona, and Soraka.
For a peek of it in LCS action, click here.
The official Riot announcement is posted here.