Erynne
I used Sakura. I suppose any Stage 5 kin with high HP, Damage and Resistance could do it. That sleep skill is nasty.
I finally managed to beat a lower level Cosmos with my Blood Grunny. I actually didn't think Blood Grunny could do that much damage but I was pleasantly surprised.
Do you know if you get anything special for beating Cosmos?
I know that Sycamorte and Castor have special items. But I haven't seen anything special from Cosmos or Sandman Rose.
Thank you kindly for taking the time to reply and help.