This Crafting enhancement

[Natsu 0]

HP Recovery (Crystal Variant, Crystal Only):Each enhancement slot of this effect heals +5 instantly. A perfect quality variant of this effect would heal +15 if all the slots are used for the HP recovery (Crystal) enhancement. The math for a perfect healing crystal would be +5*3 slots= +15 HP recovered

 

 

 

This says this, so does this  mean you can attack and use the crystal in one turn? just wondering because Next time I roll a 20 on the loot dice I will attempt to obtain one, because there are no currently active merchants I believe.

[___ 0]

You'd only get the uncommon variety from a 20 LD if it's from mob loot.

[Natsu 0]

I was wondering if you could use it instantaneously in a post and attack the enemy in the same turn as you do it, being it's a crystal. 

[Lucifer 0]

I believe it does not count as the action post as it is not stated anywhere. Much like potions, I've seen people use them and attack in the same turn.

[Life 0]

You can use health crystals and attack at the same time as health crystal do not require a post action. However, potions do and if you ever see someone not taking up a post action to use a potion you should tell them to edit their post.