IGN's Charles Onyett recently went hands-on with Torchlight II's engineer class and has since wrangled up a preview describing the hammer-wielding and pet-utilizing experience. Here are a few paragraphs to get you started:
When actually engaged in close-range combat, the Engineer’s charge bar comes into play. As you fight with normal attacks the bar builds, and consuming its charge enhances a variety of skills. The Flame Hammer skill normally slams into the ground and sends out fingers of fire to seek additional targets not singed by the initial blast. With built-up charge, more fire fingers are emitted by the blast zone, greatly boosting its effectiveness in big groups. The Ember Hammer ability normally slashes an electric arc in front of the Engineer and shatters enemy shields. If you’ve got charges stored up, damage is boosted, and unlike with the Flame Hammer skill, using Ember Hammer doesn’t actually consume charge, so you’re free to swat at enemies with the damage buff so long as you have enough mana to support it.
Other skills actually build charge alongside standard weapon attacks. Dynamo Field, for example, blasts out electric waves around the Engineer doing damage and interrupting enemies, and builds more charge the more enemies it hits. So if you’re in the middle of a big group of enemies and low on charge, you could blast out a Dynamo Field and take a few swings with your two-handed weapon to ideally build some up in a hurry and unleash its effects on the creatures trying to kill you.
Pets also play into gameplay in a significant way, following you around and helping out in fights. They also have a huge inventory and can hold unwanted items for you whenever your own is overfilled. In case you don’t want to portal back to town to sell off items, you can load up your pet and send them instead. After a few minutes the pets will return, along with any scrolls of identity, town portal or mana and health potions you ticked off on your shopping list. If you decide to drop a line into the various fishing holes around Torchlight II’s world, you can then pass any fish you manage to reel in over to your pet to trigger a transformation. The Muckfish, for instance, turns your cat into a Jackalbeast for three minutes, which gives the pet a venom attack, and the Web Fish turns your pet into a Spider, which can temporarily root foes with web attacks.