Traits

Magic Resistance. The Archon has Advantage on saving throws against spells and other magical effects.

Grove Bond. In wooded terrain, the Thornmantle Archon regains 15 HP at the start of its turn. If it took Fire damage since its last turn, this feature doesn't function until the end of its next turn.

Warden's Bramble. The ground within 20 feet of the Thornmantle Archon is Difficult Terrain (for its enemies).

Actions

Multiattack. The Archon makes three Thorn Halberd attacks.

Thorn Halberd. Melee Attack Roll: +11, reach 15 ft. Hit: 20 (3d8 + 6) Piercing damage, and the target makes a DC 19 Strength save. Failure: The target's Speed becomes 0 (until the end of its next turn) as thorns tangle around its legs.

Bramble Cage (Recharge 5–6). Dexterity Saving Throw: DC 19, three creatures within 30 feet. Failure: The target has the Restrained condition (escape DC 19), and takes 10 (3d6) Piercing damage at the start of its turn. The cage has AC 15, HP 30 and can be destroyed; it has Vulnerability to Fire damage.

Reactions

Archon's Duty (3/Turn). When an enemy within 15 feet of the Thornmantle Archon moves away from it or attacks a target other than the Archon: the Archon makes one Thorn Halberd attack. On a hit, the target's move/attack is canceled.