Vlastislav was mythological prince of Lucko (by Žatec

Žatec

Žatec is an old town in the Czech Republic, in Louny District, Ústí nad Labem Region. It has a population of 19,813 .The earliest historical reference to Sacz is in the Latin chronicle of Thietmar of Merseburg of 1004. During the 11th century it belonged to the Vršovci - a powerful Czech...

). Son of legendary Czech prince Vojen

Vojen

Vojen was the third of the seven Bohemian mythical princes between the founder of the Přemyslid dynasty Přemysl the Ploughman and the first historical prince Bořivoj...

, a brother another prince Vnislav

Vnislav

Vnislav was the fourth of the seven Bohemian mythical princes between the founder of the Přemyslid dynasty Přemysl the Ploughman and the first historical prince Bořivoj...

.

Dalimil´s chronic and Kosmas

Cosmas of Prague

Cosmas of Prague was a Bohemian priest, writer and historian born in a noble family in Bohemia. Between 1075 and 1081, he studied in Liège. After his return to Bohemia, he became a priest and married Božetěcha, with whom he probably had a son. In 1086 Cosmas was appointed prebendary of Prague, a...

 don't match in this what when was he died prince Nezamysl

Nezamysl

Nezamysl was the first of the seven Bohemian mythical princes between the founder of the Přemyslid dynasty Přemysl the Ploughman and the first historical prince Bořivoj...

. Dalimil writes:
The people of Lucko was Bohemian tribe by legends and their rulers of Přemyslids Dynasty. By Kosmas: Lucko ceased the rule of prince Neklan

Neklan

Neklan was the sixth of the seven Bohemian mythical princes between the founder of the Přemyslid dynasty Přemysl the Ploughman and the first historical prince Bořivoj...

 whose an army in the conflict by Tursko

Tursko

Tursko may refer to the following places in Poland:*Tursko, Greater Poland Voivodeship *Tursko, Pomeranian Voivodeship *Tursko, Lesser Poland Voivodeship...

scored a hard Lucko's army of Vlastislav.