Stacking magic proc is extremely important, it gives you spell shields that block range attacks and pushes melee from you. Also the only stat worth upgrading is attack, the rest just suck (crit is the worst stat you can invest in).
At first after the update, I thought the difficulty went up. But then that all changed as I got a magic proc build and just got attack stats. Now I can bulldoze through any room, kill bosses in under 2 seconds and such. (crit is the worst stat possible, the crit dmg is just added on to your attack, not multiplied, health upgrade is crap because attack gives you some hp)
DUDE Just redo lvl 1 and farm off of it. THe amount of money you start off with is the same as the amount of money you finish off with. Farming allows your rank to grow and start the next lvl with 5k of gold or more
In the tank lvls switch out the melees for a row of grenaders. The tanks will never touch them at all since maxed out grenaders have huge knock back rates.