Engineer = Bombs
Bombs = Good
The hunter has his pet to tank, yes? Well, the hunter sends his pet off to tank. Then, since your bombs do damage, you stand from afar, chucking bombs. Engineering is useful because you can break locks, make guns, make ammo, and, make money. A typical 250-300 engineering bomb costs less to make then sell, but, nobody bothers for a measly 10 silver per stack.
Ever done AV? Theres a really narrow bridge there, just big enough to be wholly affected by...a bomb. Run there, chuck a bomb, pow! You'll probably get around 1 or 2 kills.
Zomg! Theres a lock i can't open and theres no rogues handy! "Seathorium Charge". Pow. Lock gone.