Torchlight 2 Shield Build Engineer vs Siege Guardian (part 1 of 2)

This is my take on an Engineer build using a shield and a melee weapon for tanking.
I don't use a weapon for damage. Instead I use shield bash for single targets, and dynamo field for groups. For defensive skills I use healing bot, tremor, force field, aegis of fate, bulwark and onslaught.
I have zero invested in dex, a bare minimum in str (only for eq requirements). I invest all my points in vitality and focus. With dex at base I rely only on forcefield and my other defesive skills for tankiness. With both dynamo field and shield bash pumping up charge quickly, I have no problem popping the force field as often as needed. I will probably be using a very fast (0.56) one hand melee weapon with high mana leech for this build. Weapon dps don't matter for this build so I won't be investing any points in sword and board. I will probably be getting fire and spark to pump up my dynamo field.
This is part 1, where I demonstrate the play style I use against a single target boss on veteran NG+.
In part 2 I demonstrate the play style against a boss with loads and loads of adds, also on veteran NG+.
I am the appropriate level for these fights, and my gear is only mediocre.