My feedback about final boss from acts 2 & 3.

About act 2 final boss.
Almost all builds I created in patches 0.1 and 0.2 misses damage to do it.
It was necessary to play new instances of Dreadnought Vanguard to over level the boss around 2 ~ 5 levels and in meanwhile every level check the vendor to buy new items to craft something with more damage. After spending all my gold with vendor and gamble. My ever first char was abandoned. the first char of patch 0.2 was almost the same thing, but after 5 hours of trying I was able to defeat him, but not after buying a weapon in market. (almost lost my Sunday to do it)

About act 3 final boss - second form
The atack where the boss drop from sky, if you do not have boots with movement speed, you are not able do avoid the hit kill attack. It was necessary to buy from trade a boot with it.

I understand that it is necessary to change the equipment sometimes, but not check the vendor all times you up a level.

Also I feel that it should not be necessary to upgrade your equipment from trade to kill a boss.

I would also include Cunt Geonor act 1 boss with the move as the wolf he drops from above as a slam. With only 10% movespeed it's hard to evade.

In 0.1 I farmed the manor until I got 15% movespeed boots. This time in 0.2 I had no such luck, but my build was stronger and could kill him before using all my potions. I didn’t get 15% movespeed boots until level 27 this time

do you gamble? I've never needed to farm any specific zone to get thru the campaign. However I always try to get boots with as high movement speed as I can reasonably get. Usually I just gamble till I get an item that's good enough to use currency on.

I also tend to clear most of the maps during the campaign. That usually keeps me over leveled.