Beast of Burden. The opossum is considered to be a Large animal for the purpose of determining its carrying capacity.

Sure-Footed. The opossum has advantage on Strength and Dexterity saving throws made against effects that would knock it prone.

Marsupial Stare-Down. Whenever the opossum senses combat is imminent and if a visible hostile creature is within 30 feet of the opossum, the opossum stops all movement and unblinkingly stares at the nearest hostile creature within its line of sight. The target creature must successfully make a DC 11 Wisdom saving throw or become paralyzed while the opossum is staring at it. At the start of its turn, the target may make a DC 11 Wisdom saving throw in an attempt to break the paralysis. Other than affixing its stare to a hostile creature, the opossum does not move again until combat has ended.

Defensive Climb. Whenever the opossum senses combat is imminent but no hostile creature is visible to the opossum, or the hostile creature is greater than 30 feet from the opossum, the opossum attempts to climb the nearest object and remains there until combat has ended.