Obelisk | Plasma Blade > Ashbringer > Nuclear Rounds > Demolisher > Prophecy/Magnify > O Crown
This build Focuses on getting Knock, Knock! to do absolutely absurd levels of damage, the way we do this is to exploit multiple damage amplification items along with AP scaling and CDR I have managed to get Knock, Knock! to do 2400+ damage in a single burst.
Obelisk: Stacking Power you can get Typhoon, but being able to indefinitely increase your AP and also have an on demand on hit active is nice.
Plasma Blade: Attack speed, split scaling, and 40% crit at full stacks—great to reduce crit item dependency.
Ashbringer: Since Cooldowns will be low on this build may as well take Ashbringer for the ability dump potential.
Nuclear Rounds: Increases the damage of abilities up to 12-15%.
Demolisher: Obvious.
Prophecy: Not essential but adds attack speed for smoother gameplay, Magnify would honestly be the better item here as it would provide Magic Armor Shred along with an on hit effect that can be proc'd often with how much you will be spamming abilities.
O. Crown: Stat dump.