How to get S

This was such click bait.

farm low deaths

Riot purposefully doesn't tell people what the formula is so no one games the system, kind of like how they don't tell us how they officially calculate MMR.

DON'T end the game too early, lots of farm, damage, kills, few deaths (winning might help idk). Also play a character in a slightly unconventional position (don't do this in ranked pls) and still do fairly well.