[Item Suggestion] An Active CDR Item

What is an Active CDR Item? I was imagining it as vaguely similar to Zilean's Rewind, except there's a catch. By activating the item, you can reduce the cooldown of the next spell cast by X, but you add X seconds to the cooldown of the last spell you cast before that. Or maybe the cooldown added is to a random spell; not sure about what would be better. Either way, this is an item you use when you have nothing left and you're betting it all on just one last spell.

I've never put any thought into item design, and this itself was born out of a remembered dream as I was waking up this morning. So I haven't much of an idea of what existing items this builds out of, or if it should focus on offensive or defensive stats. I was thinking of possible pairing Fiendish Codex or Forbidden Idol with Glacial Shroud or Kindlegem. I also think that this is a pretty powerful item so it might require more recipe components or just a larger gold combination cost.

Thoughts:

1. I'm not sure if X should function as taking the complete cooldown (say, taking off the full 15 seconds of a spell and adding 15 seconds) or if it would need to be capped at something like 5 seconds.
2. I'm not sure if Ultimates would need to be prohibited from functioning with the item or if it would be too powerful otherwise.
3. The item itself would have a cooldown. I imagine something around a minute or longer.
4. Yes the cooldown cost added to a spell could go towards a spell not currently on cooldown. So for the two scenarios we have 1: where the spell is already on cd for 5 seconds, and then you add 5 seconds to the existing cd bringing it to 10 seconds. Or 2: the spell is not on cd so it only is disabled for 5 seconds.

The item name? Queggy's Quandry. ;) Or Luminous Glance if I'm not allowed to have a bit of an ego.

Thoughts? Comments? Constructive criticism appreciated.