"The horse is powerful."

Translation: Anne kostōba issa.

[MeinTee]

Where is the difference between kostobe and kostoba ? Bc they both rigth...

[xPsGoDWh]

They're not. The adjective in this case refers to the noun (nominative singular), and so the adjective needs to take the corresponding form (kostōba). "Kostōbe" would be used if the word "horse" was accusative singular.