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This guide contains story and final-battle spoilers, including the Gatekeeper, The Forgotten, the Spiritforge, and late-game field rewards.

Fast answer

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The final boss is the Gatekeeper on Field A4. It has extremely high health and armor, is immune to gem bombs, wasps, and strike spells, and grows up to 12 fangs. Your main objective is to destroy those fangs, then concentrate damage during the temporary vulnerability window. Build a normal kill zone for the regular waves, reserve mana and enhancement spells for the fang phase, and remove the two possession obelisks before the final wave if possible. The A4 field reward is a Journey page in Journey Mode, while Iron Wizard lists skill-point rewards; the references do not verify a special boss-only item drop.

Boss overview

Which bosses and special enemies matter?

Frostborn Wrath has one clear end-of-journey boss: the Gatekeeper. It appears on Field A4 and guards the Spiritforge. The field also contains two possession obelisks and a difficult supporting encounter, so the fight is better understood as a boss defense than as a single-target duel.

The Forgotten is the central story antagonist and appears on Field E4. Her influence is represented through enraged waves, corrupted monsters, and corrupted mana shards rather than the same stationary boss format as the Gatekeeper. Arcane Guardians are another boss-class threat. They appear on Field H4 and Field D3, where they combine high durability with armor that increases as they lose health.

Other special enemies can decide a boss attempt even when the boss itself is under control. Wraiths reduce damage dealt to enemies around them, Wizard Hunters destroy structures as they advance, Swarm Queens create eggs and release a large burst of swarmlings when killed, and Wallbreakers destroy structures in their path. Shadows and Apparitions also demand dedicated targeting because they can create additional pressure or interfere with the orb.

  • Gatekeeper: final boss on Field A4.
  • The Forgotten: story antagonist on Field E4.
  • Arcane Guardians: boss-class enemies on Fields D3 and H4.
  • Wraiths, Wizard Hunters, Swarm Queens, Wallbreakers, Shadows, and Apparitions: special enemies that can overwhelm a boss defense.
Verified versus recommended

The encounter locations, immunities, and special abilities below are documented facts. Gem colors, tower layouts, and spell timing are practical recommendations rather than mandatory solutions.

Final encounter

How the Gatekeeper fight works

The Gatekeeper is placed at the bottom of Field A4, where static beacons restrict convenient tower placement. Its listed standard health and armor are each one point below one billion. In Iron Wizard Mode, the documented values rise to three billion health and one billion armor. Those numbers explain why simply stacking ordinary tower damage is usually inefficient.

The boss is immune to gem bombs, gem wasps, and strike spells. It grows fangs through its roots, with 12 root positions available. Each fang has its own health and abilities; some launch projectiles containing spawnlings, while another documented behavior limits incoming damage to a small amount plus stored poison damage. When a fang is destroyed, the Gatekeeper takes 100 times normal damage for 40 seconds.

If the Gatekeeper survives until the start of the last wave, it becomes angry and its attacks become much more intense. That condition makes late cleanup dangerous. Treat the final wave as a deadline: finish the obelisks and as many fangs as possible before it begins, then use the vulnerability window immediately after a fang dies.

  • Do not spend strike spells or gem bombs expecting them to damage the boss.
  • Prioritize a fang when your main damage gems are ready to fire.
  • Use the 40-second vulnerability period for your strongest sustained damage.
  • Avoid leaving both obelisks and several fangs alive for the last wave.
  • Watch the lower map area because static beacons limit direct tower placement.
Important uncertainty

The available reference describes fang abilities as a range rather than assigning a complete, stable ability list to every fang position. Inspect the fang tooltip during your own run instead of assuming every attempt has identical support effects.

Practical plan

A reliable counter strategy

Start by building a conventional wave-killing area away from the Gatekeeper. You still need to survive the regular enemies, and a boss-focused setup that cannot clear linked waves will run out of time before the vulnerability phase matters. Keep at least one strong tower or trap group able to handle ordinary enemies without redirecting every shot toward the boss.

Next, create a dedicated anti-fang option. A gem with strong sustained single-target damage is preferable to relying on bombs or strike spells, because those tools are documented as ineffective against the Gatekeeper. Poison is useful as a supporting component when a fang limits direct damage, but do not treat poison alone as a complete answer. Freeze or slowing effects can buy time against spawnlings and the normal wave while your damage gems work.

Remove the possession obelisks when doing so will not collapse your main defense. They have millions of health and very high armor, so assign a separate damage source if possible. Destroying them early reduces the number of independent structures demanding attention during the boss phase.

When a fang is nearly dead, pause or reduce speed if you need to reposition, then prepare your highest-grade damage gem and enhancement spell. Kill the fang and immediately focus the Gatekeeper for the 40-second amplified-damage period. Repeat rather than spreading damage across every fang at once. If the supporting waves are becoming unmanageable, return to wave control first; a lost defense gains nothing from a perfect boss rotation.

  • Use separate jobs for wave clearing, fang damage, and obelisk damage where your mana allows.
  • Reserve Beam or Barrage-style enhancement charges for the fang vulnerability window when available.
  • Keep a control gem or spell aimed at spawnlings and other fast enemies.
  • Do not let the boss phase distract you from Wizard Hunters or Wallbreakers approaching structures.
  • In Iron Wizard Mode, expect the same mechanics but substantially higher durability and a smaller margin for inefficient targeting.
Recommended priority

A practical order is: survive the current wave, remove the most dangerous supporting enemy, finish one fang, exploit the damage window, then repeat. Change that order only when an obelisk or Wallbreaker is about to decide the battle.

Rewards and conditions

What you get for clearing boss fields

Field A4 is unlocked by beating Field A3. In Journey Mode it has 100 waves and lists Journey page 35 as its reward. The field's special encounter list includes the Gatekeeper, Shadows, Wraiths, and flying Shadows; random special entities are disabled in the documented Journey and Iron Wizard configurations.

A4's Endurance Mode lists a Wizard Stash reward connected with Field A6 rather than a unique Gatekeeper drop. Its Trial Mode lists nine skill points. Iron Wizard Mode lists Journey page 35 plus separate Iron, Brass, and Bronze rewards of 13 skill points each. These are field or mode rewards, not confirmed boss-specific loot.

The game also has broader progression rewards. Steam describes skill points from achievements, talisman fragments, shadow cores, battle traits, and wizard stashes as separate systems. The available boss references do not establish a unique weapon, gem, character, guaranteed talisman fragment, or fixed shadow-core quantity awarded specifically for killing the Gatekeeper.

  • Journey A4: Journey page 35.
  • Endurance A4: Wizard Stash reward connected with Field A6.
  • Trial A4: nine skill points.
  • Iron Wizard A4: Journey page 35 and 13 skill points for each listed Iron, Brass, and Bronze reward.
  • No unique Gatekeeper-only drop is verified by the available sources.
Mode warning

Chilling Mode changes the overall economy and difficulty, including starting resources and monster shadow-core rewards. Do not compare its farming results directly with Frostborn or Iron Wizard attempts.

Late-game checks

Counters for the other major threats

Against Arcane Guardians, expect a long fight rather than a quick burst. They cannot be handled like ordinary monsters, and their armor increases as they lose health. Keep damage continuous, use armor-relevant gem components, and protect the orb from any accompanying pressure. On D3, four are documented at the start of the last wave; on H4, one appears at the start of wave 55 in Journey Mode.

Against Wraiths, eliminate them or isolate their damage-reduction aura quickly. Against Wizard Hunters and Wallbreakers, place important towers away from their route and maintain a backup kill zone. A Wallbreaker can destroy structures in its path, while a Wizard Hunter can destroy random structures as it advances.

Against a Swarm Queen, kill the queen only when your defenses can absorb the resulting swarmling burst, or prepare area damage before the final hit. For Shadows and Apparitions, use a dedicated long-range or beam-based answer and keep the orb protected from projectiles. These counters are recommendations based on the documented enemy behaviors, not guaranteed one-build solutions.

  • Durable boss: sustained damage and armor-aware components.
  • Damage aura: prioritize Wraiths.
  • Structure threat: relocate or protect towers from Hunters and Wallbreakers.
  • Spawn burst: prepare area control before killing a Swarm Queen.
  • Flying or projectile threat: maintain a dedicated beam or long-range response.

FAQ

Common questions

Where is the final boss located?

The Gatekeeper is on Field A4, which is unlocked by completing Field A3. It guards the Spiritforge and is listed as the field's special boss encounter.

Can gem bombs or strike spells damage the Gatekeeper?

No. The documented Gatekeeper abilities include immunity to gem bombs, gem wasps, and strike spells. Use tower or trap damage, especially during the fang vulnerability period.

How do I make the Gatekeeper vulnerable?

Destroy one of its fangs. Each destroyed fang gives a documented 40-second period during which the Gatekeeper takes 100 times normal damage.

Does killing the Gatekeeper give a unique item?

No unique boss-only item is verified in the available references. Field A4 instead lists mode-based rewards such as Journey page 35, a connected Wizard Stash, nine Trial skill points, and Iron Wizard skill-point rewards.

What happens if the boss reaches the last wave?

If the Gatekeeper survives until the start of the last wave, it becomes angry and its attacks become much more intense. Prepare the fang and obelisk phase before that deadline whenever possible.

Sources

What we checked

Official listings establish current availability and product facts. Community pages are used for mechanics and build history, then labeled separately.