Tempered State

The Tempered State (Japanese 歴戦の個体 Rekisen no kotai, roughly "battle veteran specimen") is a phenomenon in monsters that heightens their aggression. Tempered Monsters are old, experienced monsters that have been living in the New World for a long time. From them living in the New World for so long, these monsters have gained the bioenergy of Elder Dragons. Every large monster in Monster Hunter: World can be affected by the Tempered State (including Elder Dragons and Subspecies) except Great Jagras, Kulu-Ya-Ku, Tzitzi-Ya-Ku, Great Girros, Zorah Magdaros, Dodogama, Xeno'jiiva, Kulve Taroth and Behemoth.

In-Game Mechanics
Tempered monsters have a metallic sheen to their bodies, deal more damage, become enraged more often, enter powered-up states faster, and are resistant to Flash Pods. Tempered monster investigations can be unlocked by gathering traces of Tempered monsters during expeditions or any quest. Scoutflies glow blue instead of green when tracking a non-Elder Dragon Tempered monster or finding a trace of one. The icons of Tempered Monsters have a purple outline.

Practical Uses
Tempered monsters are necessary to get various types of items called Streamstones. Streamstone Shards, Streamstones and Gleaming Streamstones can be used to meld decorations, Gleaming Streamstones can also be used to unlock the limit of armor upgrades, allowing to increase their defense furthermore.

Sullied Streamstones and Shining Streamstones can be appraised and they are converted into Warrior's Streamstones or Hero's Streamstones. Warrior's and Hero's Streamstones are used to augment fully-upgraded weapons; augments are special final upgrades for a weapon. There are five available options: Attack, Affinity, Defense, Slot Upgrade and Health Regen. The amount of augments available depends of the weapon Rarity. Warrior's and Hero's Streamstones can be used to agument a specific pair of weapons classes: Sword (Great Sword and Long Sword), Blade (Sword and Shield and Dual Blades), Hammer (Hammer and Hunting Horn), Lance (Lance and Gunlance), Axe (Switch Axe and Charge Blade), Shaft (Insect Glaive and Bow) and Ranged (Light Bowgun and Heavy Bowgun).

List of Tempered Material Sources
This is a rough list of each Tempered material's sources, based on the rewards of their respective quests.
 * Streamstone Shard: Threat Lv1 Tempered Monsters. (Pukei-Pukei, Barroth, Jyuratodus, Tobi-Kadachi, Anjanath, Rathian, Paolumu, and Radobaan)
 * Streamstone: Threat Lv2 Tempered Monsters. (Legiana, Odogaron, Rathalos, Azure Rathalos, Diablos, Black Diablos, Pink Rathian, Bazelgeuse, Deviljho, Lavasioth, and Uragaan)
 * Gleaming Streamstone: Threat Lv3 Tempered Monsters. (Kirin, Nergigante, Teostra, Lunastra, Kushala Daora, Vaal Hazak)
 * Warrior's Streamstone: Threat Lv2 and Lv3 Tempered Monsters.
 * Hero's Streamstone: Threat Lv2 and Lv3 Tempered Monsters.

Arch-Tempered Monsters
Arch-Tempered Monsters are even stronger versions of Tempered Monsters. They have a darker and more pronounced metallic sheen, have more health and deal more damage, sometimes have new mechanics and attacks, and their icons' outlines are red. So far, only a few Elder Dragons are known to be effected by the Arch-Tempered State (Kirin, Vaal Hazak, Teostra and Kushala Daora). Arch-Tempered Elder Dragons are event-exclusive and their quests reward more streamstones than Tempered monsters and special tickets to craft γ (gamma) armor sets and layered armor sets.