Kostos daor!

[Ser Meryn Frey]

Almost whenever Danaerys speaks in High Valyrian, some sentence end with "daor" or "kostos daor". Am I the only one to notice this? What does it mean?

[Melisandra]

It's how negative sentences are formed. kostos  (in subjunctive) 'he/she/it can', and daor, 'not'.

[iliescu]

Cool to see we are almost learning their Gotverse (Game of Thrones Universe) at last.