The second Kulve Taroth event has started in Monster Hunter: World PC along with the addition of Arch-tempered Teostra on Jan 3rd 16:00 (UTC).
The Arch-tempered Teostra can be defeated via a Rank 9 quest “The Scorn of the Sun”, which is in the Event category. You can forge Kaiser Gamma series by defeating Arch-tempered Teostra.
The Kaiser Gamma Set has many good skills like Critical Eye and Weakness Exploit, which are especially good for Affinity. You can have Teostra Technique with 3 pieces, making the set more powerful when equipped with the Drachen set and melee weapons.
In the second Kulve Taroth Siege, you can get new Kulve Taroth gear along with the previous Kulve Taroth weapons. One of the rewards you can get is Taroth Sword “Fire”, which is considered as the ultimate Longsword in Monster Hunter: World PS.
The second Kulve Taroth event will be held until 15:59 Jan 10th and the Arch-tempered Teostra event will be held until 15:59 Jan 17th.
Related: Kulve Taroth Relic Weapons you should get - Kulve Taroth Relic Weapon Farming Guide