Your Intelligence score increases by 2, and your Dexterity score increases by 1.

The Aístalain's vessels age but the host does not. They can only be destroyed by Kälsung's will.

The Aístalain can take up any shape, form and size. Generally they appear as Medium sized humanoids.

Your base walking speed is 50 feet.

Thanks to your cosmic heritage, you have superior vision in dark and dim conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.

You have resistance to fire, cold and radiant damage.

You know the thaumaturgy cantrip. When you reach 3rd level, you can cast the hellish rebuke spell as a 2nd-level spell twice with this trait and regain the ability to do so when you finish a long rest. When you reach 4th level, you can cast the darkness spell once with this trait and regain the ability to do so when you finish a long rest. Intelligence is your spellcasting ability for these spells.

You can speak, read, and write Common and up to five other languages.