If you have max up everything and can't have the Candy Drill because of the Agility achievement, take a less powerful engine, you will be slower, so you can dodge more easily.
Trick: If you are blocking on one level, just go back to the previous level then go back to the current level again. Sometimes, just a different puzzle, or a different approach, make the difference. Don't give up.
I agree aexf. I always use the katana in the old LS game, but here you have to buy it in the store then upgrade / craft it, but the DPS (damage) doesn't seem to worth the fuel price. If it cost less I would have given a try. Same thing for the Halloween weapons, I would rather keep the fuel for other stuffs. Hopefully you can have good / unique weapons by doing missions, but I have would enjoying the game without the fuel thing.
The game crashed so many times. The game judy crashed when I was on a mission and I lose all loot / experience / etc. Very annoying. The game would have been perfect otherwise of the bugs.
The most difficult for me was Guerilla.
My method is two cleric, the warrior (Captain) and the wizard (Sorcerer).
All characters have epic equipement. Health Regeneration is important. The wizard have Ignite on weapon. The wizard have a ring with -10 spell cost. If you have the whole set for the wizard, Omniscence, it's another -20 spell cost. The cleric have the ring with health bonus. The cleric have the biggest epic shield with mace. The warrior have a pole. All of them have items that have Health Regeneration.
Every wave I try to do Holy Light once with the cleric and use Lightning Storm like crazy and sometimes Fireball. The warrior was there to help mostly, remove mental curse if necessary, etc. The wizard was the main attacker. The others were secondary and only attack with the primary attack because it cost less power.