Astral runes may not be crafted via the Abyss. There is no talisman needed to access the astral altar; the astral altar is the only Runecrafting altar besides the Ourania altar that does not have a talisman associated with it.
Astral runes can also be obtained from mining a crashed star. The number of runes received depends on how much stardust the player has mined. There is a limit of 200 stardust, making 52 the maximum number of astral runes available from one star.
Astral runes may also be purchased at Baba Yaga's Magic Shop, located north of the bank on Lunar Isle. The shop stocks 100 astral runes and is located in a moving house with bird legs on it, walking east and west. Players must have a seal of passage with them when attempting to trade with Baba Yaga or they'll be thrown off the island unless the player has completed Lunar Diplomacy.