Corpse Connoisseur [Modern Masters 2017] Fate Reforged Clash Pack put a -0/-1 counter on

put a -0/-1 counter on it

I'll show you how to use that thing

Set: Fate Reforged Clash Pack Type: Enchantment Rarity: Rare Cost: {B}{G}{U} At the beginning of your upkeep

Set: Fallen Empires Type: Creature — Merfolk Rarity: Rare Cost: {U}{U} {U}: River Merfolk gains mountainwalk until end of turn

They can't be regenerated

Corpse Connoisseur [Modern Masters 2017] Fate Reforged Clash Pack put a -0/-1 counter onSet: Modern Masters 2017 Type: Creature Zombie Wizard Rarity: Uncommon Cost: {4}{B} When Corpse Connoisseur enters the battlefield, you may search your library for a creature card, put that card into your graveyard, then shuffle. Unearth {3}{B} ({3}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)