Randomness

Draws use Chainlink VRF v2.5. The number comes with a cryptographic proof that the VRF coordinator checks on-chain before your opening receives it.

The tier is randomWord mod 10,000, compared with the published odds in basis points, which sum to 10,000. The prize inside the tier comes from a hash of the opening's ID and that word.

The odds, prizes and price of a gacha cannot be changed after it is created. You can read them from the pool contract.

Expo pays for the randomness and for the settlement transactions. If the network is very busy, an answer can take longer: your paid opening stays on-chain and continues when the number arrives.