Thorns

Thorns is a defensive buff that deals 1 damage per stack to any unit that makes physical contact with the thorned unit. Contact occurs through melee attacks (the attacker takes Thorns damage) and knockback collisions (both units take Thorns damage from each other). Thorns is persistent and does not decay, providing ongoing punish against melee engagement for as long as the buff remains active.

The knockback interaction with Thorns is particularly noteworthy. When two units collide due to knockback, both units take Thorns damage from each other if either has Thorns stacks. This makes knockback-based strategies dangerous against Thorns-buffed enemies, but also means your own Thorns can damage enemies when they are knocked into you. The Spiky elite buff grants +2 Thorns to enemies (+1 for bosses), making Spiky enemies punishing to attack in melee.

Thorns damage scales linearly with stacks, so high Thorns counts can turn a defensive unit into a significant damage threat just by being attacked. Ranged attacks do not trigger Thorns, making ranged builds the natural counter to Thorns-heavy enemies. Bleed Thorns is a related variant that applies Bleed stacks on contact instead of flat damage. For builds focused on retaliation, Thorns combines well with Taunting (which forces enemies to attack you) and high Constitution for survivability, creating a tank that punishes every hit received.