Avatar of Beasts

Trampling Charge. If the Avatar of Beasts moves at least 20 feet straight toward a creature and then hits it with a antlers 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 avatar can make one stomp attack against it as a bonus action.

Speak with Beasts and Plants. The Avatar of Beasts can communicate with beasts and plants as if they shared a language.

Sure-Footed. The Avatar of Beasts  has advantage on Strength and Dexterity saving throws made against effects that would knock it prone.

Amphibious. The Avatar of Beasts  can breathe air and water.

Otherworldly Perception. The Avatar of Beasts  can sense the presence of any creature within 30 feet of it that is invisible or on the Ethereal Plane. It can pinpoint such a creature that is moving.

Spellcasting. The Avatar of Beasts  is an 12th-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 17, +9 to hit with spell attacks). It has the following druid spells prepared:

Cantrips (at will): druidcraft, produce flame, resistance, thorn whip

1st level (4 slots): cure wounds, faerie fire, thunderwave, entangle

2nd level (3 slots): pass without trace, animal messenger, beast sense, hold person

3rd level (3 slots): conjure animals, dispel magic, plant growth, meld into stone

4th level (3 slots): dominate beast, freedom of movement, wall of fire, stoneskin

5th level (2 slots): commune with nature, tree stride, scrying

6th level (1 slot): transport via plants, wall of thorns, sunbeam

Multiattack. The Avatar of Beasts makes two attacks: one with its antlers and one with its stomp.

Antlers. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 25 (4d8 + 7) piercing damage.

Stomp. Melee Weapon Attack: +10 to hit, reach 5 ft., one prone creature. Hit: 29 (4d10 + 7) bludgeoning damage.

Change Shape. The Avatar of Beasts magically polymorphs into any beast at will. The Avatar of Beasts reverts to its true form if it dies or falls unconscious. It can revert to its true form using a bonus action on its turn.

While in a new form, the avatar retains its game statistics and ability to speak, but its AC, movement modes, Strength, and Dexterity are replaced by those of the new form, and it gains any special senses, proficiencies, traits, actions, and reactions (except class features, legendary actions, and lair actions) that the new form has but that it lacks. It can cast its spells with verbal or somatic components in its new form.

The new form’s attacks count as magical for the purpose of overcoming resistances and immunity to nonmagical attacks.

The Avatar of Beasts 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 avatar regains spent legendary actions at the start of its turn.

Antlers. The avatar makes one antler attack.

Teleport (Costs 2 Actions). The avatar magically teleports, along with any equipment it is wearing or carrying, up to 20 feet to an unoccupied space it can see.

Cast a Spell (Costs 3 Actions). The avatar casts a spell from its list of prepared spells, using a spell slot as normal.