For example, if a creature dies during combat on your turn and you cast Muster the Departed during your second main phase, its last ability will trigger at the beginning of your end step
Necropotence fills a similar role because it lets you sculpt a perfect grip over multiple turns, though it has the added benefit that it insulates you against wheels by letting you refill immediately
Necropotence resolves, its controller pays the majority of their life total in order to put that many cards into their hand on the end step, and suddenly you wind up with 30+ cards in hand
The logic being that you can't deal with certain things that might befall you should you leave your opponent sufficiently undisrupted and so you use the power of Death Cloud to pro actively sabotage what is going on
it was designed to work in Two-Headed Giant matches, where your partner's Warriors that connect in combat would trigger this ability
This list is ranked by actual prices when sold, not projected or theoretical prices