I propose that each portal, along side the choice of 1 of 10 Aavegotchi, should also come with a NFT wearable that is unique to the haunt that it came from.
The NFTs will have different rarity and only a certain number will be available while opening portals.
Rarity as follows Common 45% Uncommon 30% Rare 15% Mythic 7% Legendary 3%
These drop rates can be voted on by the DAO at a future time to be adjusted but as this would be the first haunt I think it should be more rewarding.
The NFT wearables will also be decided on by the DAO as to what wearable has what rarity, this makes each of the items more likely desirable due to the nature of the community consensus.
As each portal has the choice to be used it creates value in holding onto the unused portal as chances legendary rarity can go up for a haunt if NFTs of those rarities for that haunt haven't been found.