Aggressive lane support and dueling power.
Durability and crowd control
After immobilizing an enemy champion gain defenses and later deal a burst of adaptive damage around you.
Whenever you gain a shield, your next basic attack against a champion deals bonus adaptive damage.
Restore health over time based on your missing health.
Gain permanent health when enemy minions or monsters die near you.
Creative tools and rule bending
You can enter debt to buy items.
You get free boots at 10 min. but you cannot buy boots before then. These boots give additional MS. For each takedown you acquire the boots 30s sooner.
Aftershock on Shen support makes him an incredibly strong threat in 2v2 lane fights where you're able to land your [E].
The bonus explosion damage, resists, and [Q] empowered autos make Shen a high damage version of Alistar.
Shield Bash on Shen is easily proccable with [Q] and synergizes with his wanting to auto attack for the majority of his offensive damage.
Second Wind doubles down on Shen's lane skirmishing. The mid-fight health sustain paired with your passive shield makes Shen difficult to lose a trade when a taunt is successfully landed.
Overgrowth's potential massive health scaling synergizes well with Shen's health ratios on passive shield and [E] damage.
Future's Market on supports allows you to hit early game item powerspikes that much sooner on your limited gold income.
Magical Footwear is a great rune choice on just about any champion largely for its raw gold value with no input. Think of it as effectively gaining a kill's worth of gold at 10min.