Necropotence turns life into access to cards, but it changes the timing and mechanics of your normal draw plan. You skip your draw step and may pay one life at a time to exile cards face down from the top of your library. Those cards enter your hand at the beginning of your next end step, giving black decks a powerful way to prepare a large hand.
The ability puts cards into your hand rather than drawing them. Sheoldred, the Apocalypse therefore does not gain life from those particular cards, although ordinary draw spells still work while Necropotence is in play. Lifegain from Exquisite Blood or other sources can instead provide more life to spend on future activations.
Activate before your end step begins if you want the cards during that turn’s end-step trigger. Activating after that beginning has passed means waiting for your next end step. Even if Necropotence is removed, the delayed abilities for cards you already exiled still deliver them at the appropriate time. This makes planning the amount of life to spend more useful than assuming removal erases every activation.
Whenever you discard a card, Necropotence triggers to exile that card from your graveyard, which can interfere with reanimation or other graveyard plans. Its triple-black cost favors reliable black sources, and the delayed hand refill does not provide an immediate answer in the middle of a resolving problem. Use it when the deck can spend life safely, protect the resulting resources, and convert a well-stocked hand into a strong following turn.
