First game: u were focusing too much on seraphine instead of adc or mundo, plus u are depending too much on your ultimate, zed has also good aa damage even without ulti, also I recommend u to change electrocute rune if enemy team is tanky, better use conquer or first strike instead.
Yo man please let me know if you play on european servers im currently challenger on my main and im trying to get my alt to challenger also. If you would like to duo q let me know.