Caltrops

Caltrops is a Defensive  skill in Diablo III.

In-game
Places a trap on the ground, which triggers upon enemy approach. Once triggered, slows all enemies within 12 yards by 60% for 6 seconds (both those who were in the area when it sprung and those who came after that within 6 seconds). The trap is always placed beneath the character, to a maximum of 5 traps at once, each trap lasts for 30 seconds or until sprung.

Runes

 * Hooked Spines: Slow amount increases to 80%.
 * Torturous Ground: when the trap is sprung, all affected enemies are Immobilized for 2 seconds.
 * Jagged Spikes: enemies affected by Caltrops also suffer 45% damage as Physical every second (270% over 6 seconds of total duration).
 * Carved Stakes: Discipline cost is reduced to 3.
 * Bait the Trap: the Demon Hunter gains 10% Critical Hit Chance while standing in their own active or inactive Caltrops.

Non-rune enhancements

 * Omryn's Chain (Legendary Belt): Vault also drops free Caltrops at the original location.
 * Cape of the Dark Night (Legendary Cloak): every 6 seconds, drops Caltrops beneath the Demon Hunter's feet when hit. This trap benefits from all runes and enhancements.
 * Helltrapper (Legendary Hand Crossbow): chance on hit to summon Caltrops at the Demon Hunter's location.

Passives

 * Numbing Traps: affected enemies deal 25% less damage for 5 seconds.
 * Custom Engineering: doubles the duration of Caltrops.
 * Perfectionist: reduces Discipline cost by 10%.

Trivia

 * While activated Caltrops uses the Demon Hunter cross rune, the inactive trap is using the Coven's ritual circle.