I honestly can't help you there, I guess make sure all the multipliers are set to standard if you are having trouble, increasing the difficulty will only screw you over more. Other than that, replay old levels to get more skill points, sometimes that one extra upgrade can save your life in the middle of a battle.
use 20 in bloodbound, and replay levels with red gem available so you'll get a huge multiplier, aim at 30.0 total and at least 5.03 settings, and try getting many amulets - you won't be able to get all possible, but get 900 summoned monsters for sure.
