The powerful elemental rewards you for playing a good spread of permanent types and works well with self-mill (turning your graveyard into you hand), self-sacrifice, or simply as a Sultai value commander
Suddenly your 2-mana removal spell costs 3, or your wrath costs 5, and its almost impossible to deal with what your opponent is up to
Skewer the Critics is easy enough to cast for one mana, although paying three mana still works once youre low on cards
Temur Sabertooth and Crystal Shard are efficient ways to return creatures we control, while Release to the Wind lets us recast something from exile, which synergizes with the other mechanics mentioned above
The Swarmweaver and Wickerfolk Thresher are just a couple examples of the great upgrades Reaper King decks have recently received
Crystalline Sliver Crystalline Sliver allows Sliver players to play their game without being paranoid (or at least, while being less paranoid) that disaster will strike them at any time