The most valuable aspect of the cosmic soul is the gold idol. As for the talisman you get, its like if they created a soul that contained all characters obtainable from 1* through to 5*. If you are reasonably lucky like I have been once, you might get a purple T1 which is sorta like a 3* character. Most of the time though? You get a white T1 which is the equivalent of a sand worm :/