Bip39. Firstly it is best to store it SEPARATELY from a seed. Getting your seed and also your passphrase in the identical area defeats the goal of possessing a passphrase in the first place. Entropy is an advanced function. Your mnemonic may be insecure if this element is utilized incorrectly. https://bookmarkassist.com/story18667282/bip39-wallets-https-linktr-ee-bip39-the-best-side-of-bip39-mnemonic