There are several interesting things about Kassadin's kit, especially when it comes to facing AP or squishy bosses, which makes him an invaluable asset to any team. Whenever he casts an ability using his Void Stone passive ability, he will receive a shield when doing so. As a result of this shield, he can block magic damage, making him a powerful counter to any mage he may come across in the future.
In his first ability, Null Sphere, he throws a small orb that damages and silences the first enemy hit that he hits with it. His second ability is known as Netherblade, and by using it, Kassadin's next attack is boosted in range and deals more damage, enabling him to deal more damage on his next attack. The duration of Netherblade's cooldown is reduced when an empowered attack is used to kill the target.
Those unfortunate enough to be in its zone will be damaged and slowed by its cone-shaped area of effect. At max stacks, Kassadin gains a stack of Force Pulse from abilities cast by enemies near him. The damage and slow effect of Force Pulse are enhanced when he possesses a stack of them.
Riftwalk is Kassadin's ultimate ability. His primary function is to teleport to a targeted location and deal damage to nearby enemies. In patch 3.3a, some balancing adjustments were made to this spell. It can be used multiple times but will cost more mana each time. As far as clearing jungle camps were concerned, Ekko was overpowered. As a result, his Z-Drive Resonance ability is no longer as effective against monsters as it was previously.