>>545537662
My opinions. I think all 4-piece sets suck. Three 2-piece set combos are the way to go. I think their combined bonuses offer way more for your character, plus they are not bound by elements so you can easily transfer pieces around to anybody.
>Are you supposed to craft the one that comes with elemental advantage since the chance of rolling void damage on the void memory fragment is rather low?
I assume you mean the main stat for position 5/desire/longing. It works about as well as attack% for attack-based damage dealers like Mei and Beryl. For defense-based damage, you want the element damage main stat. I don't know which is better for Tressa, the only DOT/agony character we have right now.
>Is a fragment like this good?
No, it's bad. It has two defensive substats for a set meant for damage. But again I think all 4-piece sets are bad.