Many people ask repeatedly who the best tank is. Some say Amumu, because of his great ultimate. Others say Alistar, because he has great survivability and crowd control. The truth is, every tank is great if used correctly. This is even more true with Shen- who is in my opinion the best tank if played well.
Theres a reason people always ban shen in ranked games- Hes just that good. He has great survivability, one of the best taunts in the game, he uses energy, and his ultimate has limitless possibilities. He can babysit like a champ with his taunt and vorpal blade heal/harass, and even has a decent enough shield to survive Zilean bombs.
This guide will outline MY personal play style with Shen, and offer suggestions on how to build him. As with any tank guide, it is flexible.

PROS:
- Great staying power in lane
- Incredible taunt
- Feint to absorb harass
- Heal over Time
- Decent ranged harass
- Extremely Durable
- Ultimate to prevent, escape, or cause ganks


CONS:
- Low Damage
- If taunt is missed, unable to do much
- Often banned in ranked games
- Can be stunned out of ultimate

First decision to make while playing Shen is the rune page.
There are limitless possibilities- Energy Regen runes if you want to be able to spam your taunt more, Magic Resistance runes, Armor runes, movement quintessences, health runes, or anything else you feel that you need. Additionally, many prefer to get flat value runes, but per level ones yield much more at end game- where shen truly shines.
I personally prefer to roll with:

Movement Quintessences - so you can get easier taunts, avoid a gank, or chase down stragglers.
Armor Seals - One of the two different Seals i use, which i use much more rarely. The only occasion that i would use these on is in a ranked game where i know they have at least one heavy AD champ, like Yi, who i will be playing against.
Energy Regen Seals - Highly controversial as they cost a TON to buy, and only yield roughly 9.2 Energy every 5 seconds, however that 9.2 energy is the difference between being able to land a second taunt, being able to feint out of damage, or being able to vorpal that last straggler as your team finishes them off.
Magic Resistance Glyphs/Marks - Most champions have some form of magic damage, and there are a relatively small number of item that directly counter this. Two of the best are near-useless for us (Banshee's Veil and Abyssal Scepter). Magic resistance runes provide an additional 36 MR, which is a considerable ammount.

There are of course other possibilities, and most will work fine.

Typical 0/21/9 masteries, with points in Ghost for added movement speed, Improved Exhaust over Greed (360g in a 60 minute game is a waste.), xp boost for leveling, and +10% movement on dodge.

Most summoner spells have a use on Shen
Ghost The overall best, and what I ALWAYS take. This little sprint can be used to gank, escape a gank, chase someone down, angle your taunt, and get to a team fight faster.
Exhaust Another great skill, exhaust used on a carry will make him/her nearly useless. Additionally, they are slowed, and easier to gank.
Flash A good choice on shen, where you can Flash and follow it up with a Shadow Dash.
Ignite A decent spell, however let a DPS get this as you do not need many kills. If you see nobody else on your team has it, then it might be a good idea to get. The other team might just have a Sona, Soraka, Taric, Alistar, or any other healer.
Fortify A great ability, on a long cooldown. Fortify can be used to save your towers from being back door'd, punish turret divers, and the passive assists in creep farming.
Heal A decent ability early on, but grows useless as health pools become larger.
Clarity Useless for us, we do not use mana, and thus let the support get it.
Clairvoyance A good ability if they have a jungler, can be used to prevent ganks, set up ganks, see in bushes, identify when the other team is getting Baron, and see who is going to what lane. Just be careful that they do not see the big eye in the sky.
Rally Decent early, useless late game. No real point to this ability any more.
Smite No need for this ability, only real use for a shen is to smite annie's bear or a tank creep.
Cleanse Decent enough ability if you are not planning on getting however is not as useful as ghost, flash, or exhaust.
Revive As shen, you should never die. No reason for this ability.

Shen is a tank, and being so he must be flexible in his build. Above, my build is for a balanced team.

If they are heavy AP, you might wish to consider changing

into a for added MR while still keeping a good amount of armor.
If they are heavy AD, you should replace [Quicksilver Sash] with
Another good item is however you will likely be replacing this later on, as the aura becomes nearly useless.
Make sure to buy a for Gold per 5, and then convert to a Randiun's Omen later as the game progresses.


One of the most important things to remember on Shen is to use your . The use is almost a second ability, and is great when chasing, or fighting an attack speed champion. The ideal use of this item is to Shadow Dash into a large group, follow up with the Randiun's Omen activate, and watch as your team kills them off.

::IMPORTANT:: Shen is a supporting tank, and thus you must be in that mentality. The fact is that you are not a carry, and should NEVER kill steal. This does not mean that if you can solo someone, that you shouldn't, however it does mean that if you are in a team fight, and you see your Fiddlesticks using drain life on someone who is about to die, do not try to kill him.

Early Game:
You want to harass the other team with your Vorpal Blade.
When they come close, Shadow Dash and Ki Strike then pull out. If you have a decent partner, they will also take the time to dps the target. Be careful with this, and do not use this strat if they have a stun or CC.
Always be trying to Last Hit. You need gold as much as someone else, and should be using Vorpal Blade and Ki Strike to get last hits. Do not steal from the carry though, kill your own mobs.
Try to time it so that you throw vorpal, then hit the creep once to kill it. This way, you get the gold as well as healing from Vorpal.
If your lane partner is low, let him heal on Vorpal Blade. Throw it on a tank creep, and watch his health rise.

Mid Game:
Your mid game begins at level 6. Once you hit 6, you can begin watching for ganks, or for potential ganks, and using Stand United To assist your team as needed.
Try to feed your carries, and make sure you always land your taunt.
If you have a Twisted Fate or Nocturne, it is a great strat for them to ult in on top of somebody, and follow up with your ultimate. This can turn a 2v2 into a 4v2, or a 1v2 into a 3v2.

Late Game:
By now you are not going to die. You need to be in every team fight, taunting the carries so your own can kill them. Use your Stand United On whoever is focused. be careful not to use on Zilean when he is ressing, or Tryndamere as he is using his ultimate.

When laning, it is important to level your Vorpal Blade quickly. The primary reason for this is to be able to last hit, harass, and heal.
You must also have your Shadow Dash to assist your lane partner for ganks.
When leveling, Feint if your best friend. It will save your life against things such as Time Bomb and Requiem and is great for baiting the other team into wasting mana.
You of course want to level your ultimate first, as it is no longer as powerful. Level 3 is still the same, so it is important to reach a higher level quickly.