Fleet Footwork: As a melee mage, you’re going to be punished a lot in the early game, especially since most popular champions in the mid lane are ranged. As a result, you need to double down and take all sustain possible through items and runes.
Presence of Mind: This rune is going to resolve all your mana issues, especially considering how mana hungry Kassadin is. Due to the increased mana cost on your ultimate, you’ll go through your base mana pool in a couple of seconds.
Legend: Alacrity: This is a pretty basic rune to make your auto attacks feel more fluid. It gives you the needed attack speed to execute your combo swiftly and delete opponents in the blink of an eye.
Coup de Grace: This rune acts as a finisher. It allows you to deliver even more damage to low-health targets, ensuring you execute them with your combo and get your mana back with Presence of Mind.
Taste of Blood: Taste of Blood is a simple sustain rune. It gives you some health back during short trades during the laning phase.
Ravenous Hunter: As one of the most powerful healing runes in the game, Ravenous Hunter allows you to heal back up based on damage dealt from spells.
Bonuses: +9 adaptive force, +9 adaptive force, +6 armor
Starting items Doran’s Shield
Having early durability is important for Kassadin since he’s weak until level six. Doran’s Shield will help by granting the mid laner 80 bonus health, extra health regeneration, and bonus damage to minions to ensure that you can easily last-hit. This item is going to make farming much safer for the champion early on.
During the farming phase, you are most likely going to take damage from enemy champions. Health potions heal back 150 health over 15 seconds and will give you extra time before having to back to base.
Core items Ionian Boots of Lucidity
These boots are one of the most efficient and cheapest in the game. They give you additional CDR, which scales well with your kit alongside reducing the cooldown of your summoner spells. If you’re running Teleport, it means that you’ll be able to split-push more often and join your team for teamfights.
Rod of Ages
Rod of Ages is the absolute core item of every Kassadin build. Regardless of what build you’re going for, you need this item. It grants you all the stats you need: health, mana, ability power and an amazing passive called Eternity that converts some damage taken into a mana restoration, ensuring you can spam your ultimate as much as you want.
If Rod of Ages is the toasted bread of your Kassadin build, then Archangel’s Staff is the butter on top of it. It has anything you’d want and syncs perfectly with the first item. Archangels’ Staff gives you the needed mana, cooldown reduction, ability power, and an amazing passive to convert all your mana into a temporary shield.