Trampling Charge. If the mammoth moves at least 20 feet straight forward toward a creature and then hits it with a gore attack on the same turn, that target must succeed on a DC 18 Strength saving throw or be knocked prone. If the target is prone, the mammoth can make one stomp attack against it as a bonus action.
Gore. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 11-25-39 4d8+7 Piercing damage.
Stomp. Melee Weapon Attack: +10 to hit, reach 5 ft., one prone target. Hit: 11-29-47 4d10+7 Bludgeoning damage.
A mammoth is an elephantine creature with thick fur and long tusks. Stockier and fiercer than normal elephants, mammoths inhabit a wide range of climes, from subartic to subtropical.