Not Updated For Current Season
Shen - The Eye of Twilight
Shen is a ninja, a flippin' ninja, and he is very very awesome. However, he is not a ninja that revels in the slaying of his foes but rather disrupting any enemy attack and saving his allies. This guide is to teach you how to be a true ninja, no foe will every touch you and your presence will always mean a swift victory.
Ki Strike - This is your passive and it is deceptively good. It allows for easy early game farming, and can often surprise foes with a decent amount of burst damage. Dropping a Vorpal Blade and Ki Strike on a level 1 target can drop them nearly 200 health in a second.
Vorpal Blade - This is where your damage starts and ends. End game this doesn't hit very hard, however early it can still do a fair amount of damage. It is also ranged which provides a nice bit of short range harassment without having to run all the way up to smack an enemy. It also allows you to pick off foes who might get away with just a silver of health. It's true power however, lies in the healing factor it provides. The heal on hit is global which means any friendly champion smacking the target will heal each time they strike. It isn't a very large amount of healing but it can be the difference between slinking away with 50 health and dying
Feint - A minor shield that blocks incoming damage. I am not the biggest fan of this skill but it is still very useful. It has a low AP ratio, and you are a tank not a mage, you will not have AP thus it will not block much more than the base amount. It has its uses though, see an Ashe arrow coming, pop feint and jump in front of it. However,
Feint costs only 5 less energy at max rank than Vorpal Blade. So it often ends in a choice between damage or shield. I prefer damage because frankly your enemies won't be hurting you anyway and adding a bit of damage never hurts.
Shadow Dash - This is the skill that wins you battles, lanes, and games. A bad Shen will miss with these, a good Shen will use it defensively, a great Shen will use it both offensively and defensively. The taunt does so much it is mind blowing, it knocks people out of channeled ults. like Warwick's infinite duress or Kat's Death Lotus. It will save squishies from auto attack champions, it can hold people in place for just a bit longer to get a kill. It can grab people underneath your tower and force the turret into attacking them. It does everything except your taxes, and I hear Riot is planning to patch that functionality in. I'll go over more tricks with Shadow Dance later.
Stand United - The Ultimate. This is why your teammates cheer when they see you pick Shen. It can cover a mistake, turn around a gank, allow for tower diving. At the start of the channel the shield is placed upon your friendly target absorbing the damage and the end your port directly to their location. Use it to turn around a gank on a teammate that got out of position, suddenly that 1v1 or 1v2 is even or in your advantage.
Clairvoyance - I've fallen in love with this spell, the map control it provides along with Stand United and Teleport is incredible. Having this spell is like having a mobile ward with you. Use it to spy out junglers, predict ganks, even use it to scope out opposing lanes at the beginning of matches to get more favorable matchups. As you use it more and more you'll start getting better at blind Clairvoyances useful for picking people out of the jungle moving in for ganks.
Teleport - Another spell I love, it allows Shen when coupled with his Ult to be just about anywhere at once. Stand United to save one lane and port back to yours to keep both lanes strong. Use it to quickly save towers or to back door a tower on low life.
Other Good spells
Ghost - Extra speed for escaping when coupled with shadow dash make Shen almost impossible to run down.
Flash - Flash over one wall, Shadow Dash over a second you can quickly close or create distance using the two in combination.
Fortify - I like this spell a lot, however, I play quite aggressively with Shen and it simply doesn't mesh with my play style. If you choose to play more defensively taunt combined with a fortified tower can be devastating.
Cleanse - The ability to slip out of a pesky CC can be quite useful, drop out of a Galio ult early and taunt him to disrupt it. It has many uses and with the incoming change to allow exhaust to once more be cleanseable it will only be better.
Heal - This spell isn't bad, it can cover up an early error and can make for decent bait, however it tapers off quickly and doesn't provide the entire game benefit that Teleport or Clairvoyance provide.
Exhaust - Blinding a target can be extremely useful, dropping any target to 0 DPS assuming they rely upon auto attacks. It can also provide a slow to further cripple a target trying to escape.
Bad Spells( For Shen)
Ignite - I love ignite, just not when I'm playing Shen. You aren't here to do damage you're here to prevent damage and destroy enemy lines. Ignite just doesn't fit well into his play style in my opinion.
Clarity - I don't think I need to explain this
Revive - I'm definitely NOT explaining this
Rally - It's just so weak, I'll wait until the supposed buffs before I'd consider taking this. It just is not very good and every other spell, other than say revive, is just leaps and bounds better.
The one spell I haven't listed is Smite, I haven't played much Jungle Shen so I'm not sure of its usefulness when jungling, but for laning it is very sub par.
I know there is a recommended item build up above however this needs to be expounded upon. Shen CANNOT (note: this is in all caps for a reason) build his end game items the same every single game. If you do you are not using him to his full potential. Look at what type of damage the enemy team does. If they lean to heavily in one direction either physical or magical then your build must change. The only items I use every game are Mercury Treads and Aegis of the Legion. The Mercury Treads provide an invaluable CC reduction and Aegis of the Legion is a wonderful support item that makes your team stronger and since you will be smack dab in the middle of every fight your team will benefit from the increased defensive stats.
The build above details what I generally build against a very balanced team, however most times you won't be facing a team that has a split between physical damage and magical damage. Against a heavy physical damage team I tend to build at least one extra Sunfire cape. The health and armor are just beautiful and the damage output is sneaky. Thornmail is also very nice due to its damage return against heavy auto attackers, and since your taunt forces them to attack it does a good amount of damage. Thornmail and Sunfire capes can tear apart auto attack carries in an instant.
Against heavy magic damage teams items like Guardian Angel and Banshee's Veil are extremely effective. Even though the mana part of Veil is wasted the ability to block one incoming spell combined with the health and magic resist make it extremely effective. You can pick up a Force of Nature if the game goes long enough but this is a lengthy game purchase as you should prioritize GA and BV over it.
TLDR; Follow the first item build for a balanced team comp
Heavy Physical Team
Aegis of the Legion
Heavy Magical Team
Aegis of the Leigon
Force of Nature
These are just example item builds though, just adjust to the type of damage the opposing team and there will be nothing they can do. I often find myself sitting with above 70% reduction on the primary damage source of the other team.
Early Game( level 1-9)
I prefer to lane on Shen, nearly any lane partner compliments him well. What makes Shen an extremely competent tank is his ability to farm quite well early on. Between Ki Strike and Vorpal Blade it is extremely easy to last hit minions. Rake in gold in between harassing with the Vorpal Blades and the occasional auto attack. For an early kill wait till you have close to max energy the Vorpal Blade -> Shadow Dash -> Vorpal Blade. The reason you want to pool a bit of energy before hand is that with the energy return on Shadow Dash you can often get off two Vorpal blades in quick succession for more damage. If your lane partner has a CC make sure to use Shadow Dash to either make it simple to land the ability or right as the CC is about to expire to continue to keep the enemy locked in place.
Once you hit level 6 keep an eye on your allies health and position at all times, use Stand Untied to save a teammate or turn around a fight whenever it looks prudent. It's my opinion to use it more aggressively and take a chance blowing it early than save it for the absolute best time. Wait too long and you might lose out on a good opportunity.
Mid Game( level 9-14)
This is where I find Shen at his weakest, he is still extremely powerful however his damaging capabilities have dropped off at this point but his defenses are a bit lacking without his end game items. Focus on disrupting any attacks in minor team fights with Shadow Dash and defending pushes with Teleport. Use Clairvoyance to check bushes for enemies hiding. Better to give away your positioning than wander into a team fight you aren't ready for.
This is where Shen becomes a monster, with a proper item build Shen will walk into a crowd of enemies and stroll out with ease. Their piddly damage means nothing in the face of taunts and defensive stats. Toss Vorpal Blades to mark kill targets, taunt to get your damage dealers freed up from an attack or to lock someone down into position. Stand United still has a place in team fights, use it to allow a carry to tower dive with the shield or to block damage on an incoming target.
Shadow Dash Usage
This gets its own section due to the versatility it brings. Use Shadow Dash to dash through walls, you will get through any wall provided that the length of the arrow on the other side is equal to Shen's model size. If the size is less the Dash will just pin Shen against the closest wall. When using the Dash to trap an opponent make sure to lead them slightly. There is travel time, however slight while Shen is moving so if you aren't leading the target you will miss.
If the enemy team has any sort of channeled ult, especially a Warwick hold off Shadow Dashing until you see him use it. As soon as he engages Dash through him and he will be pulled off his target. Continue to do this and he will either be forced to use his Ult on you, which is good, or have it continually interupted early. The same goes for Galio, Kat, Miss Fortune, Nunu, Fiddlesticks while he's channeling Crowstorm.
Shadow Dash is useful for ganking as well, try and come in at angles so that it is easier to force a particular enemy path to predict their movements. Cutting someone off with a Shadow Dash is a great feeling and will often result in a kill.