The Player's Handbook errata released in November 2018 patched a gap between RAW and RAI by inflicting the poisoned condition. We're exploring the impact and duration of the poison effect with an updated odds calculator.
Contagion is a necromancy spell that requires an attack roll and a "best of 5" save mechanic to inflict a disease. Is this a good spell? Check your odds against the whole gamut of monsters.