The deck starts by casting efficiently-costed creatures with strong secondary abilities including Thornvault Forrager (ramp, squirrel fetch), Osteomancer Adept (deathtouch, reanimate), Valley Rotcaller (menace, drain), Vinereap Mentor (food tokens), Bonecache Overseer (draw)
Modern isnt that fast right now, but there could be a future where your deck plans on comboing off after leading a turn on a cantrip where Serum Visions being slower matters
Tuning frequently takes another form, adding answers to your opponents
That said, Abrupt Decay can almost literally always be used against stuff like Lightning Greaves, Rhystic Study, Song of the Dryads or anything else thats bothering you
I will confess to having destroyed my own Lord of Extinction with it when my life total was precarious and it didnt look like Id survive the next attack