Killer Queen Black is a team game, and is (arguably) at its best when played with a team that is in shared voice chat.
To find teammates, start by looking in the #lfg channel or voice channels on the Killer Queen Black Discord server. Note: The Solo Queue Arena voice channel is an exception. This is for groups of people who are all joining games without parties at the same time, in order to have randomized matchups, and should not be used to form groups.