Necrotic Wound

Name	Necrotic Wound
Mana Cost
Converted Mana Cost	1
Types	Instant
Text	Undergrowth — Target creature gets -X/-X until end of turn, where X is the number of creature cards in your graveyard. If that creature would die this turn, exile it instead.
Flavor	The assassins of the Ochran distill toxins from the remains of their previous victims.
Expansion	Guilds of Ravnica
Rarity	Uncommon

Card rulings (?)

2018-10-05	The value of X is determined only as the undergrowth ability resolves. If the number of creature cards in your graveyard changes later in the turn, the target creature is unaffected.
2018-10-05	Necrotic Wound’s replacement effect will exile the target creature if it would die this turn for any reason, not just immediately after Necrotic Wound resolves.
2018-10-05	If you have no creature cards in your graveyard, the target creature gets -0/-0, and it will still be exiled if it would die this turn.
2018-10-05	Creature cards with other types, such as artifact creature cards, count for undergrowth abilities.
2018-10-05	Because tokens aren’t cards, they never count for undergrowth abilities.