ay lmao im bronze 4 dont listen to me.

At level one, upgrade Q to poke the enemy. Afterwards, upgrade W to last hit minions earlier and get more damage when the enemy comes too close. Upgrade E last because it needs charges to be used. As always, upgrade R when possible.

1) When you are engaging the enemy, use E to slow the enemy, then W to get the damage off, Q to finish.

2) When engaging an enemy running away, use R to close the gap, use E to slow, W to get damage, then Q to finish.

Kassadin's Nether Blade is used for last hitting minions and sustain mana in lane.
To clear waves, use Force Pulse and Riftwalk.

Build Rod of Ages first to get max charges by at least 25 minutes. Afterwards, build Archangel's Staff to also obtain Seraph's Embrace. Seraph's Embrace will give 1000 mana and extra AP. Building Seraph's Embrace is important to deal tons of damage late game while worrying less about mana. The next item to build is a Morellonomicon, the AP is good to have along with the CDR to reduce the cooldown on Riftwalk. The mana Morellonomicon gives extra AP due to Seraph's Embrace passive. Rabaddon's Death Cap, Luden's Echo, and Lich Bane would be good items to have because of the AP you get and Lich Bane's CDR, AP, and mana. An Ionian Boots of Lucidity would be good to pick up for the CDR.