The idea behind this character is to create a sort of anti-specialist character. As you can see, he has lots of talents that lean to a defensive play style. However he can also be played as a buff style support instead. He has many options available to help his team.
I was concerned that the level 16 talent SCV Ready! might be considered overpowered but I would argue against this, as it would be very situational and would have a long cool down. Being useful if the enemy has focused on a single lane, but next to useless if many lanes have been opened. Also his Advanced Mule talent just seemed fitting for a mechanic style character and would prove potent, especially if a regular mule was taken at level 4 (which is a tier lower than the other heroes, but again seemed appropriate for Swann). Advanced Upgrade may seem underpowered but it does affect any enemy, including bosses. Making it the ultimate defensive option.
Advanced players could take Point Defence Drone for more defensive options but it would be a situational talent.
His ultimates are also situational. Combat Drop is designed to be a CC skill, useful for objective play maps such as Dragon Shire or Sky Temple. Pulse Cannon on the other hand would suit a more aggressive siege style of play.
I am open to thoughts and suggestions so please leave them in the comments below.
However, I have two concerns. For one, I feel that the turrets should be diversified a bit more. Perdition Turret and Missile Turret both specialize in aoe so they seem similar, and I think that Devastator Turret should as a base slow enemies and gain more anti-armor capabilities as an upgrade (also, they were grenade launchers in SC2 so maybe their attack speed should be slowed and attack damage increased). Maybe since Perdition Turrets are the cheapest to build in SC2 they should have a lower cooldown and be weaker, maybe Missile Turrets can be specialized with a longer cooldown but more range. Just some ideas, but I do think that the turret abilities have a lot more potential to be diversified.
My other concern is how many of Swann's talents are structure based. I think that this could cause him to fall off in the late game or to just be generally annoying to play against. I'd suggest that instead of the Mule and SCV talents, he could have long duration summons that act like buildings (maybe siege tanks, or turrets could be placed on destroyed structures to grant increased stats and duration).
Also as a last note, the Tactical Upgrade talent seems undertuned, since it only gives 5% increased damage to a hero for 5 seconds. I think it could do with more damage and maybe a little Armor.
Otherwise, this concept has a good base and with some tweaks Swann could be a really interesting builder hero.