Trampling Charge: Suppose, as per this dnd 5e monster the elephant could move to 20 ft., straight toward the creature and after that hits it by a gore attack on its similar turn, so that particular target must be succeeded on a DC 12 strength saving throw or else be knocked prone. Any way if that particular target is a prone, then the elephant able to make a stomp attack which is highly against it like a bonus action.
Gore: By using this gore attack this elephant dnd 5e monster can make a Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 19 (3d8 + 6) piercing damage.
Also read xorn dnd 5e stats
Stomp: By using this Stomp attack this elephant dnd 5e monster can make a Melee Weapon Attack: +8 to hit, reach 5 ft., one prone creature. Hit: 22 (3d10 + 6) bludgeoning damage.
Attributes Of Elephant Monster DnD 5E
|AC||12 (Natural Armor)|
|Roll 0||Gore 1d20 + 8 3d8+6|
|Roll 1||Stomp 1d20 + 8 3d10+6|