You dont need to force a splash or chase shiny cards to build a winning decklet the packs guide you, and stay flexible
In the vast majority of games, the life that your opponent gains from you nuking their creatures with Swords to Plowshares will not amount to much, unless theyre playing a black deck with life-to-resource cards (watch out for Toxic Deluge or worse, Yawgmoths Bargain !) Swords to Plowshares isnt a particularly expensive card, and its very easy to find
For four mana, you get a 4/4 that allows you to pay three mana to blink another Creature you control
Its an easy way to show how black is ready to win by any means necessary, even if it means making deals with demons or just drawing some of your own blood
(2020-01-24) If you activate Destiny Spinner's ability more than once in a turn, the value of X may be different each time
Alongside discard outlets like Fear of Missing Out, setting up an explosive turn isnt super difficult