guys, this has something to do with the new champion that is coming, if you check out the pages of those "dead champions" you get a short animation playing:
gameinfo.na.leagueoflegends.com/en/game-info/champions/garen/
gameinfo.na.leagueoflegends.com/en/game-info/champions/zed/
gameinfo.na.leagueoflegends.com/en/game-info/champions/sona/
gameinfo.na.leagueoflegends.com/en/game-info/champions/vi/