Abilities of Shen
Spell skill priority is an important winning factor for Shen. Understanding the abilities of Shen in League of Legends is another. Below you can find all the relevant information on Shen abilities. In order for item builds you should check the build for Shen.
Passive: Ki Barrier
After casting a spell, Shen gets a shield. Affecting other champions reduces the cooldown of this effect.
Twilight Assault
Shen recalls his spirit blade to attack with it, dealing damage based on the target's max health. The attacks are greatly empowered if it collides with an enemy champion, and all collided enemies are slowed while running away from Shen.
Shen recalls his Spirit Blade. Enemies hit by the pull are Slowed by e4% while moving away from Shen for the next e5 seconds.
Additionally, Shen's next e3 Attacks deal an additional baseflatdamage plus basepercenthealth max Health magic damage. If Shen hit an enemy champion with the Spirit Blade, the damage is increased to baseflatdamage plus emppercenthealth max Health magic damage and he gains e9% Attack Speed for those Attacks.
Spirit's Refuge
Attacks that would hit Shen or his allies near his spirit blade are blocked.
Shen creates a defensive zone at his Spirit Blade for e1 seconds. Attacks against allied champions in the zone are blocked.
If there are no champions to protect in the zone when it starts, it will wait for up to e2 seconds.
Shadow Dash
Shen dashes in a direction, taunting enemies in his path.
Passive: Dealing damage with Twilight Assault or this Ability recovers energyrefund Energy.
Active: Shen dashes, Taunting champions and jungle monsters for ccduration seconds and dealing tauntdamage physical damage.
Stand United
Shen shields target allied champion from incoming damage, and soon after teleports to their location.
Shen grants an allied champion anywhere on the map between shield and maxshield Shield based on their missing Health for shieldduration seconds (max Shield at 60% missing Health). After channeling for channelduration seconds, Shen teleports to his ally's location with his Spirit Blade.
FAQ on Shen
What do you max first on Shen?
Most Shen pros max out 
Twilight Assault first.