Just after patch 7.3 was rolled out it looks like we can expect All Random Ultra Rapid Fire (ARURF) game mode in 7.4 or as Riot has stated “Soon
ARURF is one of the most popular featured game modes in League of Legends due to its fast paced and dynamic game play. Players have no mana costs, extra mobility, attack speed and nearly no cooldowns. This makes for an intense and explosive experience.
In a post on the PBE boards Riot mentioned why the game mode was not brought back sooner, citing difficulties with the new client as a main culprit. Riot also stated that initially ARURF was a test, and they also considered other options to combat issues related to URF getting boring after a few games after a meta was formed.
For those of you who love excessive damage numbers showing up on hit, unfortunately the numbers will be reverted to normal this time.
Read about patch 7.3 here.