Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Welcome to my Shen build
First i want to add information about seals - I use energy regen/per 5/per level but they're not avalaible to choose here.
To items: if you are facing a strong caster eg ryze or annie you can buy Force of Nature before first Fire Cape. You can also, what I usually do, change Randuin's Omen for Shurelya's Reverie, but as well as seals it's not avalaible to choose.
To runes:- marks - Shen's attack speed isn't very high and i can't find any better offensive marks for him
- seals - they're handy for spamming Vorpal Blade and Shadow Dash during chase
- glyphs - his ultimate is worth lowering it's cooldown as well as Shadow Dash - not only allows you to run away, but also to help your mates
- quintessences - with masteries it gives you 25% reduced time spent dead which is in my opinion very good for tank/support and allows you to butt in quicker with ulti if you died during teamfight and it's still running.
To skilling order: Vorpal Blade is usefull for last hitting minions and healing your lane mate and yourself - if in wave is big minion throw it at him, so you could regen more hp. Shadow Dash is for running away, rushing for aid you teammates if you at the moment don't have ghost or ulti, harrasing melle champs, and damaging them in early game if they'll be so tough to go under your tower - generally it's very handy. I take only 1 lvl of Feint at the begging for eg taking a part of ignite damage, or from AoE spells like I Make It Rain by Miss Fortune or Anivia's ulti. Later on you should tap it in any fight as soon as you see you can use it again - don't worry about energy, if you have seals like these and you'll do dash from time to time you should be able to do it. Once for a while you should take a look at map and if you'll see some enemies close to your teammates check if they don't need your ulti.
And that's all - i hope you'll find playing with this build as fun as I do.