[Item Concept] Wizard's Regalia as an MR sheen item

https://vignette.wikia.nocookie.net/leagueoflegends/images/6/62/Wizard%27s_Regalia_item.png/revision/latest?cb=20171223021813 Wizard's Regalia

(1050) + (720) + 530 Gold Total 2300 Gold (73.74% Gold Efficient)

+60 Magic Resist +250 Mana +10% Cooldown Reduction

UNIQUE Passive - Spellblade: After using an ability, the next basic attack deals bonus magic damage equal to 100% of base Attack Damage in an area and creates a zone for 2 seconds that increases the damage enemies take inside by 5% from attacks and abilities and reduces their Attack Speed by 15% (1.5 second cooldown).

Size of zone increases with bonus magic resist.

Technical Notes:

• The damage taken from Spellblade applies the 5% multiplier.
• The AoE does stack with Iceborn Gauntlet, but likewise does not stack any damage on the target that procs the spellblade passive.

Alternative Idea:

• Increase the gold cost to 2400 (would become 73.58% gold efficient).

• Increase the Mana to 300.
• UNIQUE Passive - Spellblade: After using an ability, the next basic atttack deals bonus magic damage equal to 100% of base Attack Damage to the target and creates a zone that erupts after 2 seconds that deals 100% base Attack Damage to all enemies inside (1.5 second cooldown). Size of zone increases with bonus magic resist.