Gold sink kdea

Hai!
We don't really have any good gold sink events. In most events we're buying energy/other stuff from other players, so amount of gold in circulation is same as before.
My idea is to add new "special" 1 week lb event once every 3-4 months. What would be the difference between this and other lb events?
1. We would buy "special" energy for gold from NPC instead of from players. These events would have "special" energy which cannot be bought for plats, only for gold from npc (lets say 250k per 1 energy). Normal energy kits wouldn't work. Of course, we would be able to drop special energy essences too, but energy craft cost should be increased aswell.
2. There would be special lockeds which can be opened only for gold in NPC too. These lockeds would have typical drop for lockeds = mythic/arcane/set gear, vanities, legendary stuff etc. Prices for example could be 1.2m for 3xpull and 1.8m for 5xpull.
Tbh, it's hard to imagine plat free event, so there's an option of making plat/keys lockeds too, but with different drop. Plat sales (auras, eggs etc) can stay as usual.
3. Special event points/speed/dmg etc elixirs for gold in NPC. It has to be gold sink event so...
4. All lb vanities from these events should be tradeable. Non tradeable lb rewards would mean that the only people who are losing gold are lb runners. If all of these lb vanities were tradeable then non lb runners could buy them, so they would waste their gold too.

PS. Gold sink idea*