A swap on the pool produces one card for the address that traded. What the card contains is decided by a SHA-256 hash of the transaction that created it — nothing else. No server chooses it, and no result can be adjusted after the fact.

Anyone can recompute a card from its transaction hash and check the site against their own arithmetic. That is what Verify is for.

Cards left unopened for six hours expire. Cards have no monetary value. They cannot be bought, sold, transferred or claimed.