Pros
*High sustain
*Hex gunblade busts W and aa damage
*high damage output in 1 vs 1
*strong againts melee champs in mid
*strong against almost all mid champs if mastered
*high damage harassment with W

Cons
*Squishy (if not buying spirit visage)
*weak after full combos
*long ranged champs can burst you realy easy, stay focused and wait
*E and flash to engage R instead of protobelt
*the harassment is based on auto attacks (poor range compared to most of mid champs that have long ranged skills)

Harassment:

W pasive (Wp)(5th charged auto attack) with dark harvest , W active (Wa) and auto attacks (aa) are the key for this.

Basic combos:

Wp + Wa when the enemy is behind creeps (try to Wa and turn back quickly when Wp impacts)
Wp + Wa + Q (Stun) + aa + aa
Q + Wa
Q + Wp + Wa (Stun) + aa + aa
E + Q + Wa (E is just for positioning when the enemy is too far away a/or behind creeps, when the Q lands use Wa while returning)

After buying hex gunblade and stacking some souls for dark harvest the basic combo Wp + Wa inflicts a lot of damage

Stun Combos:

Wp + Q + Wa (Stun) + aa + aa (try to Wa when Q lands for fast stun and start auto attacking immediately)
Q + E + Wp (Stun) + aa + aa + Wa (when landing E, turn back, press E again and Wp to stun and auto attack from a safe distance)
E + Q + Wa (Stun) + Wp + aa + aa (use after evading skills)


Delete combos (R):

E + R + Q + Wa + Wp + aa + aa + hex gunblade + aa + aa + Wp
R + Wa + Q + Wp + hex gunblade + aa to death
Wp + Q Wa (at same time) + E + R + hex gunblade + aa + aa
Wp + Q + E (Stun) + R + aa + aa + aa + hex gunblade (+ aa + Wp + Wa if survived and trying to escape)
E + R + Zhonya's + Wa (use in teamfights, try to E everyone before using zhonya's)
Q + Wp + Wa (Stun) + E + R + hex gunblade + aa to death

Emergency or surprise R combo (susceptible to ganks after full combo or being killed if it wasn't enough)

Flash + R + E + Wa + Q + hex gunblade.
Flash + R + Q + Wa + Wp + hex gunblade + ignite + E to escape
Flash + R + Wa + Q + ignite + hex gunblade + Zhonya's
Flash + E + hex gunblade + R + ignite + Q + Wa (when the enemy is too far away)

Against ranged champs:

Max Q first, forget about W harassment and stack dark harvest for late game.

Hex gunblade sustain helps a lot.

Try to land a Q, then E to avoid and get near to Wa and turn back. repeat and wait an oportunity (no mana or gank) to engage with full combo

if ganked:

1. E (run)
2. Wp + Wa + E (for running away) + Q (stun) on jungler
3. Q + Wa + E (Stun) on jungler and run away
4. Q or Wp (on midlane enemy) + R + Zhonya's

i'm not a native english speaker (as you can see!!) so feedback on the guide OR the grammar is apreciated!

Thanks for reading!