Ancient Elephant

Legendary Resistance (3/Day). If the elephant fails a saving throw, it can choose to succeed instead.

Trampling Charge. If the elephant moves at least 20 feet straight toward a creature and then hits it with a gore attack on the same turn, that target must succeed on a DC 16 Strength saving throw or be knocked prone. If the target is prone, the elephant can make one stomp attack against it as a bonus action.

Gore. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 25 (3d10 + 10) piercing damage.

Stomp. Melee Weapon Attack: +10 to hit, reach 5 ft., one prone creature. Hit: 25 (3d10 + 10) bludgeoning damage.

Trunk. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 16 (2d8 + 8)bludgeoning damage.

Thundering Trumpet. Each creature of the elephant's choice that is within 120 feet of the elephant and aware of it must succeed on a DC 16 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the elephant's Thundering Trumpet for the next 24 hours.

The elephant can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The elephant regains spent legendary actions at the start of its turn.

Detect. The elephant makes a Wisdom (Perception) check.

Trunk Attack. The  elephant makes a tail attack.