New/Old users interested in past Ti exclusives, will upgrade their compendium level to get access to the optional purchase. A high enough price that people have a massive incentive to purchase this years compendium. Maybe my pricing is too low. This will also serve old players that missed out.

Example reach 255 can buy past prestige's for optional purchase 25$-$35 each, level 355 IO arcana optional $35, Level 600 Eminent revival optional $50-$100. Etc. All are untradable/unmarketable exclusive to Ti. Adding gems to past prestiges like lion's prestige for upgrading will solve upgrading problems.

Past compendium sets (Cavern sets) with unlocks. Maybe 10-20$ each as much time was put into them to get the unlocks. Creeps 10$, terrains $10, weathers 10$. All untradable/unmarketable. Gaben Voice $10. Level 1.

I think that will ensure people get levels for compendium, and new users can get access to beloved prestige/Ti exclusive items. All still Ti exclusive untradable/unmarketable of course.

Collector's Cache sets are a much harder issue. As people invest in those sets to trade. Unfortunately, I can't see a solution for the cache sets.

Edit, Just read this. Maybe the antimage/sniper/gyro/sniper/timersaw/dragon knight sets of past battlepasses, tides stingray mask, other nick nacks, could be linked to a level and obtained aswell, Example, Excluding the "Golden Ornithomancer Mantle". As it was added to a chest "2016 trust of the benefactor", was for sale on the market. None are listed atm.

Anything that was untradable/unmarketable. As the traders will have no problem with it. (unless they are account sellers, against TOS).

As highlighted by the latest chest blunder, Valentines Treasure,, which released a cache set. There was an uproar about the Collector's Cache 2015, Ti5 set 'Flowing Entropy' spectre set being in there. But nothing much mentioned for the untradable/unmarketable sniper and gyro set. So, looks good I'd say.