As with refinement, tempering is bound to an item slot and not to the item itself, so increase tempering level whenever you can, there is no need to save up resources for later. Maximum possible tempering level for a particular item will rise at refinement level 5 of that item and every 2 levels thereafter - refinement level 5, 7, 9, 11… I would like to add that in-game description of this temper-refinement connection is wrong, it says that every 5 levels of refinement the tempering potential will increase, but that’s not the case. Maximum tempering level is represented as a water level inside a circle. As you temper the item water level will rise, once it reaches the top of the circle item will be at maximum tempering level. Maximum tempering level is also represented by the numbers inside the circle. It is important to mention that maximum tempering level isn’t affected by item quality - basic, magic, rare and legendary items all have the same tempering potential.
Tempering will increase different attributes depending on the item type:
-Main Weapon and Side Weapon: Attack, Elemental Attack, and Defense
-Necklace and Ring: Attack, Elemental Attack and primary resistance type (the highest resistance value for a particular item)
-Helmet, Armor, Gloves, Boots: HP, Defense and primary resistance type (highest resistance value for a particular item)
If you don’t have enough resources to temper all equipment to the maximum level, my suggestion would be to prioritize: Main Weapon, Side Weapon, Necklace, and Ring, because these increase your damage dealing potential. If you’re really low on temper stones, you could even prioritize just one weapon for tempering, and use it as your primary source of damage (at least until enough temper stones become available for both weapons).
How to get Tempering Stones:
-Normal Battle – your primary source of temper stones, use auto-loot option
-Team Instance – will often have temper stones (besides other stuff) as a reward
-Valor Store – if you are really in a deficit or have tons of valor, otherwise it is a better idea to invest valor in other stuff (primarily in high tier weapon shards, if you unlocked those through PVP)
-Lost Treasure Event – Not recommended, high fortitude cost for a small gain
It is possible to change “how much” you want to temper a piece of equipment in one click by taping +1, -1 or Min, Max icons. I really don’t find this function useful and never use it.
IMPORTANT NOTE: Unlike with most upgrades, tempering cost will stay the same throughout the game.