Sylas is a melee burst mage assassin with unique ability to steal enemy champions ultimate, he is not that good early on lane, so thats why hail of blades is extremly good for aggresive laning phase, u can play very aggresively, but not against counter champs that i mentioned that are aps, such as lb and ahri. If they hit their e ability youre very easy to kill, but anyways u're gonna outscale them, so just by pushing side lanes and making other enemys to rotate so u have 4v5 with is great especially with your nashors tooth and passive.