Deal 7% more damage to low health champions. Gain AD/AP after kills or assists.
Aurelion Sol's damage mechanics rely almost entirely on his ability to position himself well from moment to moment. The Movement Speed burst from Phase Rush lets you chase and stay in perfect range for follow-up [W] hits.
Sol's massive lac of mobility makes him incredibly vulnerable to jungle ganks and mage assassins like LeBlanc. Nullifying Orb helps you survive those ganks and all-ins so that you can scale into the mid game without being way behind.
Again, mobility is the name of the game for Sol. Combined with his [E] passive Movement Speed, Celerity will grant you very reliable bonus AP.
Waterwalking is a great rune to take on Sol when you're looking to get the early shove and roam to the side lanes for map pressure.
WhyPresence of Mind
Presence of mind on Sol allows you to pick up multiple kills and assists in teamfights and keep your [W] on for extended periods of time without fear of mana constraints.
WhyCoup De Grace
Coup De Grace is the go-to rune for consistent damage amp when looking to finish off targets.
Sol's large area of influence on fights thanks to [W] allows you to pump out massive damage to any target.