Assassin/Ninja lvl 35 build help

i don't know what good gear is at this level, any advice would be greatly appreciated

 

Adventurer set, 2x morph topaz, durums serenity and hashr claw is what i used iirc

 

for lvl39
https://wynnbuilder.github.io/#4_0bF0bG0bI0bH0cF0cF0qm00A0CM0C0U0l0R070d000010008G
WynnBuilder build:
> Adventurer's Cap
> Adventurer's Tunic
> Adventurer's Pants
> Adventurer's Boots
> Morph-Topaz
> Morph-Topaz
> Union
> Durum's Serenity
> Hashr Claw [w4w4]
for lvl35
https://wynnbuilder.github.io/#4_0bF0bG0bI0bH0cF0cF0Ux00A0ts0B06140J060Z000010008G
WynnBuilder build:
> Adventurer's Cap
> Adventurer's Tunic
> Adventurer's Pants
> Adventurer's Boots
> Morph-Topaz
> Morph-Topaz
> Vindicator
> Durum's Serenity
> Tempo Tanto [w4w4]

 

How do you get union?

 

either on the market or open a bunch of tier 3 or 4 chests