What do I give up when I evolve?

Dr. Dickie loves gold so you will have to give him all of it in exchange for a visit in his Evolution Chamber. This means all the gold you still have in the inventory as well as the upgrades that you bought with gold throughout the game. So all your weapons, armors and minions will be reset to level 1 and all your gems de-fused back to level 1 as well. You will also have to give up all the skill points you won by upgrading items, so your skill tree will be empty after evolution, but this allows you to reset it and try another build.