Mammoth

Mammoths are the largest of all beastial herbivores. They are easily recognizable their opposable trunks and at least one pair of ivory tusks protruding from their mouths, and thick coats of fur to protect themselves from the cold of the far north.
Another notable feature of mammoths is their intelligence and memory. In fact, they have been known to hold grudges against poachers or hunters for months and even years enacting revenge as the herd comes in full force to attack their settlment or village. Such behavior is reflects the strong familial bond amongst a mammoth herd as each member fiercely defends its own, collectively raises their young, and mourns the loss of a herd member.
In general, mammoths tend to be largely unaggressive, albeit quite wary, towards humanoids. However, mammoths have been known to be quite welcoming to Seiðr circles and other groups in tune with nature. In fact, they have been known to regularly communicate, visit, and even aid these individuals in the protection of their environment. If a mammoth herd has had negative encounters with humanoids in the past, they will become extremely territorial upon future encounters. When provoked, mammoths rarely fight alone unless separated from its herd. While defenders of the herd engage their enemy; the others guard and escort the young or elderly to safety away from the fray.

Mammoth CR: 6 (2,300 XP)

Huge beasts, unaligned

Armor Class: 14 (natural armor)

Hit Points: 138 (12d12+60)

Speed: 40 ft

STR

24 +7

DEX

9 -1

CON

21 +5

INT

7 -2

WIS

11 +0

CHA

6 -2

Skills: Skills Athletics +10, Perception +3

Damage Resistances: Cold

Senses: passive Percepion 13

Challenge Rating: 6 (2,300 XP)

Siege Monster. The mammoth can deal double damage to buildings and structures.
Endurance. When the mammoth fails a Constitution saving throw that deals damage, it takes half damage. On a success, it takes none
Ice Walk. The mammoth can move across and climb icy surfaces without needing to make an ability check. Additionally, difficult terrain composed of ice or snow doesn't cost it extra movement.
Charge. If the mammoth moves at least 20ft. straight towards a creature and then hits it with a gore attack on the same turn, the target takes an additional 13(2d12) damage.
Opposable Trunk. The mammoth is able to wield and interact with objects using its trunk as a bonus action. The trunk has a reach of 10ft. for the purpose of grappling or retrieving an object.

Actions

Gore. Melee Weapon Attack, +8 to hit , 5ft., one target. Hit: 33 (4d12+7) bludgeoning damage. Creatures must succeed a DC 18 Strength saving throw or be knocked prone. As a bonus action, the mammoth can make a stomp attack against a prone creature.
Stomp. Melee Weapon Attack, +8 to hit , 5ft., one prone target. Hit: 25 (3d10+7) bludgeoning damage.