This is our proprietary skill rating calculation. This has nothing to do with official game ranking or MMR.
The purpose is to show player skill levels relative to other players, not estimate MMR.
PASSIVE - You gain additional Magical Power and Lifesteal scaled from missing Health. This caps at 70 power and 10% Lifesteal at 40% Health.
PASSIVE - Basic Attacks and Abilities gain 15% additional Magical Power against targets below 60% Health.
PASSIVE - Enemies hit by your abilities have 40% reduced healing for 5 seconds.