The declensions for the word vandis, nominative and accusative, singular and plural, are as follows:
- vandis (nominative, singular)
- vandissa (nominative, plural)
- vandis (accusative, singular)
- vandissa (accusative, plural)
As you can see, for the singular and plural, the declension for the nominative and accusative case are the same. You can find more information here: https://wiki.dothraki.org/High_Valyrian_Noun_Declensions#Fifth_Declension ; vandis is declined like the word tubis in that table.
Sȳz biarves se geros ilas! (Good luck and good bye)