At the moment there is very little incentive to look for common/magic drops of particular items with good stats… i.e. looking for a katana to use for crafting a nice fast melee weapon.
So how about a RUNE OF LUCK… Use it in the same way you use a Rune of Shattering but it has the opposite effect. i.e. use it on a magic or common item and it creates a totally RNG rare version of the same item - a full re-roll but guaranteed rare.
This would allow to reuse common / magic items from both drops and gambling… almost a second try at getting a better roll before attempting crafting.
Drop rate & cost of this rune could be the same as the rune of shattering.
probably have to factor the rarity based on its ability to roll a great rare item with any consistancy. If its gonna roll a multiple T4/5 affix rare on a regular basis then it definitely would need to be rarer that a shattering rune…
You could say it has a chance to roll up a tier per rune used? Like 4 runes of luck would make it possible for t4 runes on your item. 5 runes would make possible t5 affixes, etc. Just an idea. Kind of like this one, @vapourfire