Q - Twilight Assault Spirit Blade pull and AA-empowerment. Shen pulls his spirit blade to his location and once it arrives, he gains 3 empowered basic attacks with bonus range. Pulling the blade through an enemy increases the magic damage of the empowered attacks, slows the enemy and grants Shen bonus attack speed. This is Shen's core ability, it's his primary damage source and way to move the spirit blade. As Shen, you're always trying to pull the blade through enemy champions.
W - Spirit's Refuge Protective area around blade that blocks attacks. Shen primes his spirit blade, and creates an area around it that will activate after 2 seconds or if an allied champion walks in it. When active, the protective zone blocks all enemy basic attacks targeted at ally champions. This includes any on-hit effects or spells that count as basic attacks like Ezreal's Mystic Shot. Shen's W might be hard to use correctly at first, but when mastered, it's an extremely potent ability that can turn around fights.
E - Shadow Dash Dash that damages and taunts. Passive energy recovery. Shen's E has a passive and an active. Passively Shen recovers energy when dealing damage with his Q or E. The amount of energy recovered scales up on champion levels 1, 4 and 12. The active is a dash that deals physical damage based on your bonus health and taunts enemy champions or monsters for 1.5 seconds. It can cross terrain and can be combined with Flash for lightning fast engages.
R - Stand United Global teleport with a shield. Shen’s ultimate is a global teleport. He shields an ally champion and channels for 3 seconds. After channeling, Shen and his spirit blade blink to the target ally. The shield scales based on the target's missing health and can last for up to 5 seconds. Stand United is Shen's identity. His playstyle revolves around saving teammates from across the map like a super hero.
P - Ki Barrier Passive self-shield on ability cast. After using an ability, Shen gains a shield. Ki Barrier's cooldown is reduced every time you affect at least one champion with an ability, i.e. pulling your Spirit Blade through an enemy with Q. It's important to note that the shield comes after the triggering ability's effect is finished. So with Q when the spirit blade reaches Shen, with W when the protective zone disappears, with E when you finish dashing and with R when you complete the teleport.

My runes are build in a way that will make my Shen deal a lot of damage with his q. Building divine and having my runes give me that little bit of damage can affect my game in two ways:
a) I kill the man easily
b) I fail because I'm not tanky enough
But there is a way to prevent option b and that is to practice and learn combos on Shen which will improve your game also timing is a great thing to learn and can positively affect the game for you!

The Taunt-Flash combo, known as E-Flash. This is Shen's most known mechanic. To perform the E-Flash combo, cast E (Shadow Dash) and use Flash before de dash ends. It's a simple combo but it can start fights from longer distances, maximizing the E's range.