Spike Trap

Spike Trap is a Devices skill of the. It can be considered an offensive variant of Caltrops.

In-game
Unlike defense-oriented Caltrops, Spike Traps are designed to deal direct damage. A trap is placed at the cursor location (as opposed to Caltrops placed at the Demon Hunter's location), but does not explode outright, even if an enemy is within its blast range. Instead, the next skill that costs Hatred (other than Spike Trap) will immediately detonate all traps.

Note that Spike Trap has quite a short blast radius.

Only 4 traps can be placed at a time; placing more will despawn the oldest of the previously deployed ones.

Runes

 * Echoing Blast: increases the damage of each explosion to, Chills enemies hit for seconds (slowing them by ), and turns the damage into Cold (unlocked at level 27).
 * Custom Trigger: increases damage to . The traps will be detonated by Hatred generators instead of Hatred spenders (unlocked at level 30).
 * Impaling Spines: increases damage to and changes the damage type tp Physical. When the trap is deployed (not detonated!), all enemies in its blast radius are immediately immobilized for  seconds (unlocked at level 39).
 * Lightning Rod: damage type changes to Lightning, and blast radius increased to yards. When the trap is triggered, it also releases a pulse of lightning that arcs to all other traps within  yards, hitting enemies caught in line. Each enemy hit will suffer  damage as Lightning over  seconds (unlocked at level 46).
 * Scatter: decreases damage of each trap to, but simultaneously lays traps per cast for a single charge, with a 30 degree scatter (they are placed right next one to another, but their blast areas do not intersect). Maximum allowed number of traps is also doubled. Hatred cost of the cast, cooldown and maximum number of charges do not change (unlocked at level 55).

Non-rune enhancements

 * Chanon Bolter (Legendary Crossbow): periodically causes enemies to be lured into the Traps.
 * Helltrapper (Legendary Hand Crossbow): chance on hit to summon a Spike Trap at the target's location.
 * The Demon's Demise (Legendary Hand Crossbow): the blast from Spike Trap will damage all enemies it hits again after 1 second for same damage.
 * Trag'Oul Coils (Legendary Bracers): Spike Traps gain the Impaling Spines rune in addition to any other, and are deployed twice as fast.

Passives

 * Numbing Traps: affected enemies deal 25% less damage for 5 seconds.
 * Custom Engineering: doubles the duration and increases maximum limit of Spike Traps by 1 (to 5).

Trivia

 * Just like Caltrops, an inactive Spike Trap will be lying dormant in a Coven ritual circle.

Development
Originally, prior to 2.4.2, this trap would instead have a maximum of 3 at a time, and would detonate upon enemy approach (with a 1.5 seconds arming time), exploding up to 3 times.

Until patch 2.4.3, it was one of the six skills in game (along with Overpower, Dashing Strike, Sentry, Avalanche with Tectonic Rift rune and Furious Charge with Dreadnought rune) that used Charge system, allowing multiple casts to be performed at once using accumulated charges. The charge replenishment time was reduced by cooldown reduction. In 2.4.3, its charges system and cooldown were removed altogether.