Ah, from the first post by Leviathan:
"Upgrading and Evolving Cosmic Talisman
Cosmic Talismans can be powered up and evolved like normal Talismans, but cost a bit more. They will also sometimes feature unique Cosmic Evolution Materials which will earnable via Events every month."
Symbiote mentioned his cosmic talisman needs 5 x Demon Seed to be upgraded to Level 3. Presumably we'll find out more in the other events this month.