Bip39 Generator. First and foremost you must store it Individually from the seed. Owning your seed as well as your passphrase in a similar place defeats the objective of using a passphrase to start with. BIP39 specifies a list of 2048 words from which the mnemonic phrase is decided on. https://mixbookmark.com/story4286457/bip-39-https-linktr-ee-bip39-a-simple-key-for-bip39-unveiled