Genshin Impact 3.6 update will bring Kaveh alongside Baizhu as a 4-star character to the game, and you will be able to pull him from his banner using Intertwined Fates. If you are successful in doing so, he won't be very effective immediately, and you will need to ascend him using his ascension materials to get the best out of him.
You can get the full list of ascension materials required to ascend Kaveh here, and one of these is the Mourning Flower, which is the local specialty of Sumeru and has a 1-star rarity. You will need a total of 168 Mourning Flowers to ascend Kaveh completely, and here are the locations where you need to go to find them.
Genshin Impact Mourning Flower: How To Farm
As per leaks by Honey Impact, the in-game description of Mourning Flower describes it as the "Crimson flowers that can bloom even on ancient battlefields or flourish in the depths of the desert. Its drooping flowers seem to be in mourning for heroes long past." It is pretty evident from the description that Mourning Flowers are found in the desert area of Sumeru; however, as of now, we don't know the exact location of them as they will be introduced in the game with Genshin Impact 3.6 update.
