Instead of using 'Hearts of Wood' for Epic TR, introduce 'Stones of Destiny'.
The stones will come in basic and +1, +2, etc variants. The number indicates how many additional Epic Destinies will be bonded during the TR.
Sell for mucho TP through the store (naturally)
Assure us that they do drop in quest but are very very rare. (honest)
But make them PURCHASABLE with EPIC TOKENS!!!!!