[Item Concept] Looming Malice

So just a random source of inspiration to attempt to create an item. This is my first item concept but hopefully it isn't that bad. As always I am open to input on such things so feel free to leave some. Anyways lets get onto it.

Looming Malice Build Path - Haunting Guise (1500 gold), Aether Wisp (850 gold) + 750 gold = 3100 total gold

Stats +70 Ability Power +300 Health +7% Movement Speed

UNIQUE – EYES OF PAIN: +15 magic penetration UNIQUE - Malice: Damaging spells against shielded enemy champions will mark them with 'Malice' for 10 seconds. Once the target becomes unshielded or the duration ends the mark will detonate dealing 65 - 150(+20% AP)[60 base + 5 per level] magic damage to them. The damage increases by 10% for every second the target remains shielded maxing at 50% against unshielded targets or 100% against still shielded targets. Enemy champions can only have one mark of 'Malice' applied to them at one time.

Updates

• Old description removed, "Damaging spells against shielded enemy champions will mark them. Once the shield on the marked target ends or is destroyed, the mark will detonate dealing magic damage to them."- 5/24/2017
• Damage changed from 150 - 250(+25% AP)magic damage to 65 - 150(+20% AP) magic damage - 5/24/2017
• New effect, "The damage increases by 10% for every second the target remains shielded maxing at 50% against unshielded targets or 100% against still shielded targets." - 5/24/2017
• Added for clarity, "Enemy champions can only have one mark of 'Malice' applied to them at one time." - 5/24/2017