[Golem Goblinx2 Healer Goblinx4 Healer Goblinx2 Golem] with all the vital upgrades worked very well for me =D - I haven't even tried cleanse warlock or elemental xD
2000(2259)pts/$1000 Length=2 Height=2 Sleigh=1 Glider=8 Boost=2 Fuel=4
5000(5445)pts/$5000: Length=2 Height=6 Sleigh=2 Glider=3 Boost=3 Fuel=7
15000(18439)pts/$25000: Length=1 Height=4 Sleigh=2 Glider=4 Boost=8 Fuel>9000!!!
This is what I used to get the hard badge, good luck :)
The puzzle in room "3 right 5 up" is very easy, but I just wanted to mention it can be even easier because of a small bug that allows you to move through a square without changing it (quickly click another adjacent square before the skull reaches the square you want to skip). =P
Insane difficulty is super easy if you use defense class, and use the "shield bash" a lot. The enemies will barely be able to hit you and it doesn't really consume mana. Your mana will drain quickly if the enemies hit you shield, but if you use many short shield attacks they won't be able to hit you (hold shield anyway if the.. alpha something bigger enemies use their charge attack or you're fighting the dragon). Hope this helps :)
My shark: Starts too early (obviously cheating), never stops accelerating, uses steroids and that just might explain how he can use obstacles to actually BOOST his speed :S xD