When ever i play Sona i first unlock her W then at level 2 i get her Q but the first time i use the q there is server wide lag for est 3 sec which has lead to deaths
doesn't seem to be connected to starting items i have mixed those up but could be mastery's.
When i'm and get my W at level 1 then my Q at level 2 it causes every player on the server to experience lag.
It happens every game
PS. sorry don't have good video capture i know you want proof but i don't have that ability.