Active: Kassadin fires an orb of void energy in the target direction that deals magic damage and silences the first enemy hit.

Active: Kassadin empowers his next basic attack within 4 seconds to have an uncancellable windup, gain  250 bonus range, deal bonus magic damage, and restore (5% / 15%)  missing mana.
If this kills the target, the cooldown is  reduced by 50%.

Nether Blade resets Kassadin's basic attack timer.

Passive: Each time Kassadin or a nearby champion casts an ability, he generates a stack of Force Pulse, stacking up to 6 times, upon which the next cast becomes empowered to consume them all.

Active: Kassadin emits a pulse of void energy in a cone in the target direction that deals magic damage to enemies hit and slows them by 30% for 1 second.

Empowered Bonus: The damage is increased to 140% and the slow to 90%.

Active: Kassadin blinks to the target location, dealing magic damage to nearby enemies upon arrival. He then generates a stack of Riftwalk lasting 12 seconds, refreshing on subsequent casts and stacking up to 3 times.

Riftwalk: For each stack, Riftwalk deals 50% bonus magic damage at an additional 200%  mana cost.