New end game items. Game breaking or brilliant?

So i was toying around with the idea of items that are designed 100% around the end game. in other words items that would take players most of the game to be able to get, but would have insanely high stats/ abilities on them. My thought process was to start with Items that share a unique passive. So something like , , and + a small fee to combine them, and you get something that does like 300-325% base attack damage + 50% AP in an area (maybe plus a slow zone) on your next basic attack after casting a spell. It would cost 10K gold, the 3 item costs plus 367 combining cost. The same idea could be done with other items that share a unique passive.

The basic idea is that if the game goes long there is something that can be done with all that extra gold players are going to be carrying around. In theory a player could "rush" the item but it would come at the cost of the rest of their normal item build, plus the passives don't "combine" till you get the super expensive item.

Thought i'd just throw this idea out there and see what people thing