Intro:
With the recent Shen buffs, he is now (again) a top tier champion.
If built and played properly, he can be a powerful bruiser, a strong support, and a sturdy tank all in one package.
This build is designed to optimize Shen's tool kit for the most cost effective Shen possible.
Jungling with Shen, I've found, is the most effective position for him. Though he isn't the fastest jungler and can't kill dragon or baron as easily as some others, he does boast awesome sustaining power and is an effect ganker (especially after level 6 is achieved). He is very mobile and can take a beating while providing damage output comparable to most bruisers while paying nearly nothing towards offensive stats.
Build highlights and explainations:
The thing that jumps out at readers first, I'm sure, is the use of the under rated item 
Stinger. First off, who has ever heard of a ninja without a sword... This item is actually very amazing, but is over looked frequently because it only provides 2 (usually counteracting) stats and can only build into a 
Nashor's Tooth which isn't a desirable item for most champions.
Stinger is however, an optimal item for Shen. Shen really needs a little bit of AS in his build as his 
Ki Strike is one of his main damage outputs unless built with AP. Stinger also provides the benefit of 10% CDR another great stat for Shen. The reason I build a Stinger over other AS options like 
Wit's End is the cost. The humble Stinger only costs a meager 1090 gold. The 
Recurve Bow costs almost as much 1050 and doesn't not provide the CDR (the same amount of AS). That's 10% CDR for 40g (pretty solid!).
The stinger is the only offensively oriented gear choice we will make on Shen and will greatly improve his DPS while the CDR will also improve his mobility, utility, and defense.
I also start the jungle with a
Doran's Shield. This is really an awesome starting item for Shen as he inherently life steals and his damage is boosted by the bonus hp on this item. The armor in the jungle is also a good benefit (especially since I prefer the %hp seals on Shen). The hp regen on the item will keep Shen topped of as he goes- giving him even more sustaining power.
Rushing
Warmog's Armor on Shen is also a key concept. Many other builds will build items such as
Sunfire Cloak on Shen. This item has both offensive and defensive components on it and the pattern costs 800g and only 20hp and no extra armor. Instead, this build focuses on HP and lots of it early on to get the most out of
Ki Strike. We need to be careful of %hp damage because we are doing this, but on the whole it works very nicely. The sooner we get a
Warmog's Armor the sooner our %hp runes become an asset and the build comes together.
Masteries:
For Shen, I enjoy 6/21/3 masteries.
The bulk of our points are in the defense tree to make Shen very beefy (and hence effective).
I then get 3 points in utility for the 10 extra energy (very handy).
The remaining points I stick into offense for a little extra AP and AS.
Skill Selection:
No need to reinvent the wheel on this one.
Get all 3 skills first so you have them for the first gank or if you run into an enemy in the jungle early on.
Vorpal Sword is Shen's spammable ranged damage and it heals him. It's his best jungling tool and damaging ability...level it first.
Next we level feint. Feint appears to be just a shield at first but it also doubles the reset condition on ki strike. This makes it amazing and worth leveling second over shadow dash.
Finally shadow dash. Not that it's bad at all, but it's cd sets it behind the others.
We get the ult at 6,11,16 (obviously).
Runes:
For marks i take magic penetration since most of shen's damage is magical
For quints and seals I take %hp since hp benefits shen so much and we already are building a ton (% bonus of a ton is substantial).
For glyphs I take shielding as magic damage is your biggest threat (% based) but you won't see much of it except on ganks (hence getting /level will be better by the time you need it.)
Closing Remarks:
Shen is all kinds of over powered now...take advantage of him before he gets nerfed into the ground (again) and make use of this guide in doing so.
I hope you enjoyed the read and I've inspired you to try out a Stinger 
Shen soon.
Enjoy!
Build Guide
Discussion (1)
Heart of Gold. The heart will give you a nice hp and gold boost.
Mercury's Treads for the tenacity and mr along with movespeed 2.
Force of Nature this item has extreme MR and has good synergy with high hp champs like Shen.
Randuin's Omen to bolster my armor, give a little more CDR and the nice active/passive. This is a great item for Shen as it allows him to disable fighters and AD carries even more than usual.
Trinity Force.
