I will be adding more in the future

Pros
+ Extremely Strong if Fed
+ Potent Gank Potential
+ Amazing play-making with ultimate
+ Great splitpusher and duelist late-game
+ High damage early game
+ A good Shen can be the deciding factor in a game
+ Annoying as hell to play against
Cons
- Slow clears early
- No innate sustain
- No innate wave clear
- Bad Shen can lose the game for the team
- Not the best mid game without items
- Lots of bad matchups
- Only as good as the player

I am.... Sigh.. well, I am a noob. A beginner. Only mastery level 6 on , but who cares...ANYWAY, this Shen build works. I swear. You might need to change the runes but I've had a lot of success with this build. Lethal Tempo and Press The Attack work as well. Always start your bot side buff first, as you will have a better leash. However, Red is more beneficial to Shen, as he doesn't benefit from the mana sustain that Blue gives. After clearing your first buff, go Wolves and top side buff. Then look to gank top/mid or contest scuttle. If you manage to land taunt or flash-taunt (in the combos section) a Shen gank will usually result in a kill or a flash, unless you're banking for someone like Kassadin running Teleport pre-6 (trust me, I have personal experience with my Kass main friend). If no lanes are open to gank, go to contest scuttle. If you're lucky you might get scuttle, if you meet the enemy jungler, however, if it's someone you can duel, walk/taunt up. to them and start hitting them. HOWEVER, this is risky because one of their laners might come up to you and at that point you'll have no choice but to use Flash. The safer method is to call one of your laners to come and help you, then you might be able to pick off a kill. Afterwards, clear Gromp/Krugs and recall. By this time you might have enough to buy Tiamat. After Tiamat rush Bloodrazor (Red Smite).

Around the mid game look to farm and farm, as Shen isn't too good mid game without items. Gank when you can and tax your laners (smite the cannon minion or something) and help them push in the wave. If your ultimate Stand United is up, look to pull off some cheeky ultimate plays around the map in between farming.

Late game is all SPLITPUSH. Shen is a very natural splitpusher because of his global ultimate and so he can participate in team fights too without having to recall. Look to push to at least their inhibitor turret while everyone else is teamfighting. If they send some people to stop you, taunt away and even use your ultimate to get away, cheeky cheeky! If the enemy is pushing into your inhibitor and beyond, however, play defensive with your team instead of splitpushing.

Now for some combos! Perhaps the most well-known Shen combo is the taunt + flash. To do this simply taunt and flash as the dash ends, catching your enemies with the very tail end of it.
To save an ally on low health, ult them and as soon as you land, activate W because your spirit blade lands on TOP of you when you ult. Then proceed to disrupt the pursuers with a taunt into Q + AA, but if they are high health or the entire team is there (happens sometimes) just run with your ally. However if you are a good Shen player you should know to not ult a target with a pursuer who is high health or there are multiple pursuers. Just let them die, it's not worth your ultimate to spare a couple seconds of your teammate's life just to have you both die.
When dueling, MAKE SURE YOU HAVE THE CAPABILITY TO DUEL THE ENEMY, then start off with a taunt into Q + AAs. Once your passive shield runs out deploy your W, however, YOU DON'T ALWAYS HAVE TO USE YOUR W. If they are already starting to run away, don't use your W. If say a Master Yi keeps right-clicking, laugh in his face and deploy your W as much as you want.

I know this was a pretty short guide and it doesn't have nearly enough information, but I hope it provided enough and good luck on the Fields of Justice! I might update this in the future if it receives good feedback!