You need to account for the damage increase from your primary stat and 300% increased damage is 4 times higher damage not 3 times.
2set raiment is better than 2set sunwuko, you should try to get the 2 shenlong weapons, they should be easy to get by upgrading rares.
Shenlong is much easier to get and with raiment 2set you can pretty much go to t6 or even t7 immediately if your toughness and healing is good enough.
U6 relies on too many items to be a short term goal, but as a long term goal it's a beast.
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