Multiattack. The elephant makes two Gore attacks.
Gore. Melee Attack Roll: +8, reach 5 ft. Hit: 15 (2d8 + 6) Piercing damage. If the elephant moved at least 20 feet straight toward the target immediately before the hit, the target also has the Prone condition.
Trample. Dexterity Saving Throw: DC 16, one creature within 5 feet that has the Prone condition. Failure: 17 (2d10 + 6) Bludgeoning damage. Success: Half damage.