Idea for AP fighter item

AP fighter itemization is very very sad. It often boils down to being too high in damage and low in survivability, or too low in damage and effectively a tank. Here is my attempt at creating an AP fighter item (Based on Black Cleaver):

Build Path: +1200 Gold (Total cost is 3500) Void-Touched Blade: +60 Ability Power +500 Health +20% Cooldown Reduction Unique Active: Teleport to a nearby target location. If you teleport away from an enemy champion, you are slowed by 20% for 3 seconds. Cooldown: 80 Seconds. Unique Passive: Dealing magic damage to a target reduced their magic resist by 4% for 8 seconds, stacking up to 24% magic resist reduction at max stacks (6)

Reasoning:

1. Stats: AP items are all very high AP and low health, so I aimed to make this item lower on the AP spectrum, while also not being 300 health or less like the rest of the AP-HP items. I made the HP higher than Black Cleaver as this item costs 500 more gold to make, and I made AP higher as AP isn't as applicable as, or scale as well as, AD.
2. Active: I wanted to mimic the Black Cleaver Passive by adding a cool little active. This active would function as a way for the AP fighter to get close to their target. As some AP fighters (most noticeably Diana and Mordekaiser) can have troubles getting to their target (in the case of Diana, without her ult), the teleport can be an invaluable way to start their assault. I wouldn't be against giving them the rage passive though as the teleport seems a little weak.
3. Passive: The same as the Black Cleaver Passive except stacks last a little bit longer. Maybe the penetration should be higher, and the stack time reduced idk.

Tell me what you guys think about this item. Would you build it on Zac/Diana/Morde if you got the chance?