Festering Newt is a common Creature — Salamander card from Iconic Masters (IMA), collector number 90. Current market price: $0.06 (foil $0.25), TCGplayer market prices via Scryfall.
When this creature dies, target creature an opponent controls gets -1/-1 until end of turn. That creature gets -4/-4 instead if you control a creature named Bogbrew Witch.