Torchlight 2 Engineer Build Guide

A proper gentleman need be well-educated, practice good dental hygiene, and always be prepared to set large numbers of ruffians screaming through the air in flames with a nice whack from his trusty tools of mayhem. This build will make you a master of the melee, the foremost at fisticuffs; turning iron jaws to glass with the power of smoke and steam.
Gear Choice
Great weapons are essential, you need not tarry with diminutive odds and ends. Greataxes, greathammers, greatswords, and polearms will all serve your purposes nicely. Bonus fire damage, bonus electric damage, and armor penetration are always fine choices.

Stat Points
Having your wits about you will carry you just so far – you also need to be strong of arm to handle the kind of hardware this build requires. Two points per level, and often more, should go into Strength. Do not neglect Vitality, either, as you will more often than not be right in the thick of things, being attacked from all sides. Focus is important as well, to keep your machines of destruction running on pure, high-grade mana. And throw Dexterity a point now and then, just so it doesn’t feel left out.
Levels 1-25
The key skills that make up this well-oiled demolition engine are Flame Hammer and Ember Hammer (Blitz tree). The former is your raw damage stand-by, while the latter will clear away those pesky shields right quick. Remember to use Ember Hammer only when your charge is high and the need is immediate, as it does not build charge. Passives like Heavy Lifting and Supercharge (Blitz), as well as Fire and Spark (Construction), also demand attention, increasing your pain output with large, unwieldy objects and giving you more charge to kick those damage skills into overdrive.
Once Onslaught (Blitz) unlocks at 21, add it to your priority list as it provides excellent battlefield mobility, a must for any front-line fighter in Torchlight 2.

Levels 26-50
Ember Reach (Blitz) should join your arsenal as a way to lock down those pesky ne’er do wells that have the audacity to turn and flee from an honorable duel. Storm Burst (Blitz) can give you a differently-flavored movement skill, but I find it too redundant to use at the same time as Onslaught, so grab a respec potion if you want to try it out and pick one or the other. Dynamo Field and Overload (Aegis) make a devastating combo with Onslaught, but will require you to neglect your passives to get them up to speed.
Levels 51-100
You should now be able to start maxing your passives, or the Onslaught/Dynamo Field/Overload combo, depending on what you let fall behind in the earlier levels. You can start funneling some points into Coup de Grace (Blitz), and if you find yourself dying a lot, some survivability skills like Charge Domination and Bulwark (Construction), or Aegis of Fate (Aegis). Emberquake (Blitz) is always tempting, of course, and layers well with your other AoE attacks as it does not consume charge. Just be sure you have the mana to support it. Tremor (Aegis) is also a less all-or-nothing alternative to Overload, but I would not recommend taking both.