How about scaling difficulty faster (so you actually die before level 30 on your first try)? And maybe instead of saving gold (i never spend it in the shops to save it for permanent upgrades) bring the red crystals back. Then use gold as "in game" currency for health, attack, and maybe random spells/items and the crystals to buy character upgrades. And finally instead of mass health for completing quests and arenas (makes them a no-brainer instead of a choice) just give crystals (or if you don't want the crystals back, more gold)
Hey i found a way to make the gun (when your out of all ammo) better. When firing constantly switch your weapons and you will fire like 3-5 times faster! rate up to keep alive!