If
you cast
Mephistopheles, your
Avatar is
banished. Mephistopheles is now your Avatar. He retains
Unique rarity, Demon type, and
Air element, but he's no longer a
minion and only an Avatar. Your current and maximum
life remain the same. Notably, you won't be able to
sites normally because Mephistopheles doesn't have that
. You will still be able to cast spells because Avatars are spellcasters as one of their
. If you manage to
Mephistopheles without casting him, then he will not replace your avatar, but his second ability will still function.