[6][7] Among his graduating classmates were Inga Salurand, Lauri Lagle, Mari-Liis Lill, Laura Peterson, Ursula Ratasepp, Britta Vahur, and Sergo Vares.
[8] While still a student, Kübar made his stage debut at Estonian Drama Theatre in Finis nihili, a play written by Madis Kõiv.
For his performance in Orpheus Descending by Tennessee Williams (directed by Nübling), Kübar was voted Young Actor of the Year 2013 by the professional journal Theater heute.
The two-man show, with Belgian actor Benny Claessens, caused some controversy for the amount of nudity and the homosexual theme, but garnered positive reviews.
[13][14][15] In February 2018, Kübar performed with NTGent, director Florian Fischer and actress Lien Wildemeersch To name herstory, which was an adaptation of Don Quixote: which was a dream (1986) by Kathy Acker.
The press called Kübar's idiosyncratic style perfect in its content, inventor of a new language that, despite its bizarre character, communicates immediately with the audience.