How to make this ?
Can i reroll this affix into adventure??
not on an Eternal Item because 
. in the later part of the post is a list of the few crystals that can be used on Eternal Items.
some Set Affixes can be rolled on any Classes Items, some can only be rolled on a certain Classes Items and then Jaspered to anther Class if necessary, and lastly the remaining Set Affixes can only be found on Looted Items. check this post .
I believe the 4 newest Sets can only be found on Looted Items.
How about the set affix ? How can i change it ?
Kyanite, Quartz, and Amethyst don’t work on Eternal Items. so you can’t take any affix off of an Eternal Item, and you can’t put a Set affix onto an Eternal Item.
if you look at the first post and look down at the part with the Discussion Only Cheaters & Hackers, it lists the Crystals that can be used on Eternal Items.
also, in the first part of the post, 9 crystals are listed that can be used on Pets, and only Calcite can be used on Eternal Pets. as you can see, Amethyst can’t be used on Pets, so you would either need to find a Pet with the Set Affix you want, or take a Set affix off of one of your other Items and replace it with the Set affix you want, unless you want a Set affix that can’t be rolled with Amethyst, which means you need to find an Item with the the Set affix you want.
I looked at the Crystal Crafting Restrictions Post, and you can either find an Item with Adventurer Set or use Amethyst to put it on an Item. but not on a Pet or an Eternal Item/Pet.