Your search for "Harsh Mercy 39" revealed the following:
Harsh Mercy (CMM) from Commander Masters, available at 401 Games Canada. Rarity: Rare Finish: Normal Artist: John Matson Card Text:Each player chooses a creature type. Destroy all creatures that aren't of a type chosen this way. They can't be regenerated....
Harsh Mercy (ONS) from Onslaught, available at 401 Games Canada. Rarity: Rare Finish: Normal Artist: John Matson Card Text:Each player chooses a creature type. Destroy all creatures that aren't of a type chosen this way. They can't be regenerated.
Harsh Mercy (Foil) (ONS) from Onslaught, available at 401 Games Canada. Rarity: Rare Finish: Foil Artist: John Matson Card Text:Each player chooses a creature type. Destroy all creatures that aren't of a type chosen this way. They can't be regenerated....