On top of the card advantage Sephiroth gives you, it also has the Blood Artist effect whenever any creature dies
Rule 2: Bottoming a card is a commitment Putting a card on the bottom doesnt delete it, but it does say: Future me can deal with this later. In a 60-card format, bottoming matters a lot because you will realistically see more of your deck
Sure, you lose life in exchange, but being able to take a problematic enchantment the second it becomes a problem is a huge boost to black decks
A whole lot more effect than Night's Whisper and well worth that wait
Within the wilds of Theros there are civilizations of centaurs and satyrs, hulking hydras, sphinxes, dragons, sirens, manticores, cyclopes, giants, and pegasi