A very needed tank Item

There are very few methods to deal with Attack speed based champions. The games I have been playing lately have been flooded with Devourer junglers and Vaynes. There are 39 champions that can boost Attack speed. Most of which can do so above the 40% mark. There are 4 that reduce attack speed. There are 2 items in the game that reduce attack speed and 13 that increase attack speed (one of which is boots!). This is a HUGE discrepancy. I don't think the reduction to the tank items was bad per say, but tanks are missing a key item they need to be able to build, one that focuses on AS reduction.

Here is my go at such an item:

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+ + 600 gold = Frostlord's Bulwark Armor + 100 Health Regen +200% Unique Passive - Point Runner: Builds up to 20% movement speed over 2 seconds while near turrets and fallen turrets. Unique Passive - Cold Steel: Whenever you are hit by a basic attack the attacker will have their attack speed reduced by 8% for 3 seconds stacking up to 4 times. When the attacker gets 4 stacks they are slowed by 20% for 1 second.

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I would love some feedback on such an item and would also love to see other ideas on Attack Speed reducing items. Perhaps a more powerful Aura then frozen heart? Or an active on the item? There really are a lot of options and I would love to see other's take on such an item idea.