There will be various Polish artists. One of them is Margaret who participated in Poland's national selection for Eurovision 2016 with her song 'Cool Me Down'. She finished in 2nd place.
As foreign artists there will the Swedish winner of Eurovision 2016 Måns Zelmerlöw and the Spanish artist Alvaro Soler who was one of the biggest summer hit in 2015 by his song 'El Mismo Sol'
You can buy the tickets here: magicznezakonczeniewakacji.pl