Innistrad: Midnight Hunt

Intrepid Adversary | Creature | Human Scout | Lifelink When Intrepid Adversary enters the battlefield, you may pay {1}{W} any number of times. When you pay this cost one or more times, put that many valor counters on Intrepid Adversary. Creatures you control get +1/+1 for each valor counter on Intrepid Adversary. | Viktor Titov

Spectral Adversary | Creature | Spirit | Flash Flying When Spectral Adversary enters the battlefield, you may pay {1}{U} any number of times. When you pay this cost one or more times, put that many +1/+1 counters on Spectral Adversary, then up to that many other target artifacts, creatures, and/or enchantments phase out. | Uriah Voth

The Meathook Massacre | Legendary Enchantment | | When The Meathook Massacre enters the battlefield, each creature gets -X/-X until end of turn. Whenever a creature you control dies, each opponent loses 1 life. Whenever a creature an opponent controls dies, you gain 1 life. | Chris Seaman

Tainted Adversary | Creature | Zombie | Deathtouch When Tainted Adversary enters the battlefield, you may pay {2}{B} any number of times. When you pay this cost one or more times, put that many +1/+1 counters on Tainted Adversary, then create twice that many 2/2 black Zombie creature tokens with decayed. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.) | Tuan Duong Chu

Bloodthirsty Adversary | Creature | Vampire | Haste When Bloodthirsty Adversary enters the battlefield, you may pay {2}{R} any number of times. When you pay this cost one or more times, put that many +1/+1 counters on Bloodthirsty Adversary, then exile up to that many target instant and/or sorcery cards with mana value 3 or less from your graveyard and copy them. You may cast any number of the copies without paying their mana costs. | Heonhwa Choe