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 Physical Power equal to 2% of your Maximum Mana.
PASSIVE - For every non-ultimate ability on cooldown you gain a stack of Cruelty. Each stack provides 7 Physical Power and 2% Physical Lifesteal.