Kassadin is a melee Ap caster which thrives on 1v1's again squishy champions because he can burst them down like a gun against a watermelon. The best way in using kassadin is harassing which is his best skill because of his silence/Null Sphere. His best way into bursting down enemies is to Rift walk - silence/Null Sphere and Force Pulse however his force pulse only activates when abilities are used close to him.

For runes i get 5 mark cool down reduction runes for his spam-able silence and his easy escaping from his ulti/rift walk, full seal and gyplh ap runes because of his early kills for mejas stacks. if you aren'y gonna get dorian ring then get mana regen runes instead of ap runes because he is mana hungry if you spam spells .

Kassadin is a melee mage which does high damage with his silence and is a boss at getting away with his ulti. He is one of the best for picking off 1 unit at a time because of his burst with cool down reduction runes and items. The best way into killing targets is to riftwalk, null sphere, force pulse and finally nether blade. The dorian ring will get him the mana regen and ap which is perfect for a caster like kassadin, if you aren't fed you have to get boots first or else you wont be able to get away fast enough and you can get bursted down like a gun against a melon, after you must get a lich bane because of the procs that the sheen can get and the mana which the lich bane gives you, the deathcap will just make you a more powerful and much stronger, Last item must be a rylai's scepter for the slow with the null sphere and again there is mana with that item.

Pros:
he is one of the best bursters in the game
he can farm alot with his rift walk with force pulse
he is a master of getting away
if fed he is unstoppable

Cons:
he is a melee champion
he is squishy but not so squishy like vayne
if kassadin is silenced he will be useless but still efective

when in a team battle try to focus a caster because of his burst with his Null Sphere and his force pulse. Again if in a team battle you must target a high priority target because he can destroy squishes and he maybe can kill tanks.

always farm when your minion wave if over run byt he enemy minion wave. the skills to take out the minions are his Rift Walk then his force pulse because the Rift walk is an AOE skill to a target location and his force pulse goes in a cone shape.