Bip39 Checksum. Entropy values need to be sourced from a solid supply of randomness. What this means is flipping a good coin, rolling a fair dice, noise measurements etcetera. Will not use phrases from guides, lyrics from songs, your birthday or steet handle, keyboard mashing, or nearly anything you believe https://zopedirectory.com/listings641886/bip39-passphrase-generator-https-linktr-ee-bip39-details-fiction-and-bip39-word-list-pdf