Dex and xtals for almost LW Assassin for 2023

As the title stated, My first Sin was level 280ish and built on almost LW. I wanna get some advice on how much Dex I can and should invest for the current 2023 built

My stats so far:

Agi=256(this is max for me)
Crt=400(main focus)
Int=290(main focus-ongoing)
Vit=50(planning to stop around 350)
Str=1(undecided, but focus apos)
Dex=1(currently planning to have)
Gr=100(reached 2000 eva with buffs)

AI of choice:
1st - Magic Evasion%

Equipment of choice:

•Spec throw:
Raiju Jiulong 200 - gives atk up per vit, max was 500

Atk up= (0.01 x VIT x 100)
Melee to water=20%
Melee to Wind=10%

Cutting hat II - gives atk up per CRT
Sadly, I only have NS

Atk up= (CRT x 1.2)
Cdmg up= (CRT x 0.06)

•Additional
Horned Helmet 4th upgrade

Atk up= (CRT x 0.60)

•Body Armor
Vanputt up- it has both maxHP and delays, best armor as a startup

Maxhp up= (Dex X 16)
Maxhp limited to 5000, 313 Dex in total

•Ultimi up- For offensive

•Thief Garb- For poison, (Cause yarde,3i, and MG likes to hugged the wall)

•Special:
Pre PS- anything could help on survival and delays
Post PS- anything could help on offensive and delays

For Xtal As of the moment, I have no ways of using Ideaus; have no ways of getting Sauro II, USAM, and so on... Can I just use melee to elem%?

I noticed from grinding Yarde with Ouroboros that it has a decent damage 100k - 300k from my current level🤔

Then I could use normal elem throws if I have a dex? 🤔