Ohmwrecker Item Design Rework- AP Pushing Item

Ohmwrecker + + + 900 Gold = 3550 Gold +90 Ability Power +400 Mana +10% Cool Down Reduction +6% Movement Speed UNIQUE Passive: Upon leveling up, restore 20% of your maximum mana over 3 seconds. Upon destroying an enemy structure, restore 50% of your maximum mana over 5 seconds. UNIQUE Active- Tower Drain: After channeling for 1.5 seconds, begin to channel and drain the life from the target enemy structure, dealing 25 (+5 per level) (+55% AP) magic damage every second to the tower. Convert 5% of the damage dealt into health and 10% of the damage dealt into mana. (600 range, 650 unit tether range) (15 second cool down)

I really like the development of Ziggs Bottom Lane. It's a rather unique play style so I thought "Hey, why don't we actually support other Mages potentially going Bottom Lane with an item?" Ohmwrecker seemed like a perfect fit since Divers don't really need more help diving and Tanks already have a strong tower destruction item in Zz'Rot Portal. That left the AP class feeling left out of tools specifically made for taking towers, so I thought maybe this item would be a cool update to Ohmwrecker to try and introduce more Mages to Bottom Lane. It's quite costly and doesn't provide any benefits to a Support so any potential Support abuse is mostly gone (unless they are a "Support", upon which they probably aren't trying to be a Support anyways and won't be providing their team with a Sightstone and all the other unique Support trinkets). Thoughts?