Enter A Bip39 Passphrase A person illustration of manually creating entropy can be flipping a coin. But if an attacker gives you a coin that may be weighted a little bit in favor of heads, your Preliminary source of entropy should have been corrupted. Keep it within a safe place: https://kingslists.com/story19814071/bip39-number-of-words-how-much-you-need-to-expect-you-ll-pay-for-a-good-bip39