Copypaste from previous thread, thank you for your hard work user
Did some research on Tempered Monsters in MHW
And collected them in this post for easy digestion.
What is a tempered monster?
Tempered monsters are the endgame/postgame monsters in MHW.
They are just like the regular monsters, but have increased attack power (enough to one shot geared hunters with certain attacks.)
Tempered monsters also have a purple outline in their icon and leave blue tracks.
Investigations with tempered monsters also have purple reward boxes.
Categorically the tempered monsters fall into 3 groups:
Pukei-Pukei
Barroth
Jyuratodus
Tobi-Kadachi
Radobaan
Paolumu
Rathian
Anjanath
Rathalos (Might be tier 1, could not confirm)
A.Rathalos
P.Rathian
Diablos
B.Diablos
Odogaron
Legiana
Bazelgeuse
Lavasioth
Uragaan
Nergigantte
Teostra
Kushala Daora
Vaal Hazak
Kirin
Higher the tier, the better the rewards.
Note: the highest rarity drops are exclusive to the 3rd tier.
Where to fight them?
Tempered monsters are primarily investigation only, there are also few quests that pit you against tempered monsters.
Tempered monster investigations are generally unlocked by gathering tempered tracks in expeditions. (These tracks seem to always spawn in the same spots)
You can also them the same way as normal investigations when hunting tempered monsters. (break parts, gather tracks) But the chance is very low.
They are also found under Investigations section when responding to S.O.S.
Why to fight them?
Tempered monsters drop streamstones in rewards and tempered monster investigations reward either streamstones or feystones.
Streamstones are used to augment Armor. They also come in different rarities.
Streamstones can also be used at the melding pot to create new random decorations out of the old ones.
You can also rarely get "warrior's streamstone" from 2nd tier upwards, they come in different types like Axe (Switch Axe & Charge Blade), Ranged (Bowgun's & Bow), etc, and can be used to augment the corresponding weapon types.
Warrior's streamstones also have a rare version called "hero's streamstone" needed for augmenting Tier 8 weapons.
Note: that lower rarity armor require lower rarity streamstones to augment and lower rarity weapons have more augment slots.
Feystones turn into decorations when identified, and come in several different rarities.
This is the only real way of getting rare decorations, and the fastest way of getting decorations in general.
There are decorations for at least some of the set bonuses present in the game. (Bonus charge level for bow, Extra damage on non elemental weapons, etc).
Augmenting quick and dirty
Weapons can be Augmented following ways:
Increased attack (+5 raw)
Increased affinity (+10%)
Bonus defense (+10)
Extra slots (potentially upgrade existing slot)
Heal on attack
Note: Numbers can potentially vary depending on weapon type.
Rarity 8 weapons have 1 augment slot, Rarity 7 has 2 and Rarity 6 has 3.
Each augment also requires different plates and gems for different monsters.
Note: A weapon must be at the end of it's upgrade path to be augmented.