diff --git a/Includes/CubbyTower/Commons/TowerData.hpp b/Includes/CubbyTower/Commons/TowerData.hpp
index c531475..d34f9b8 100644
--- a/Includes/CubbyTower/Commons/TowerData.hpp
+++ b/Includes/CubbyTower/Commons/TowerData.hpp
@@ -14,6 +14,9 @@ constexpr static int ARROW_TOWER_LV1_PRICE = 100;
 
 //! The price of arrow tower at level 2.
 constexpr static int ARROW_TOWER_LV2_PRICE = 200;
+
+//! The price of collatz tower.
+constexpr static int COLLATZ_TOWER_PRICE = 500;
 }  // namespace CubbyTower
 
 #endif  // CUBBYTOWER_TOWER_DATA_HPP
\ No newline at end of file
diff --git a/Includes/CubbyTower/Components/CollatzDamage.hpp b/Includes/CubbyTower/Components/CollatzDamage.hpp
new file mode 100644
index 0000000..28e7eff
--- /dev/null
+++ b/Includes/CubbyTower/Components/CollatzDamage.hpp
@@ -0,0 +1,23 @@
+// Copyright (c) 2021 CubbyTower Team
+// Chris Ohk, Minkyu Lee, Minjune Yi
+// We are making my contributions/submissions to this project solely in our
+// personal capacity and are not conveying any rights to any intellectual
+// property of any third parties.
+
+#ifndef CUBBYTOWER_COLLATZ_DAMAGE_HPP
+#define CUBBYTOWER_COLLATZ_DAMAGE_HPP
+
+namespace CubbyTower
+{
+//!
+//! \brief Damage struct for Collatz tower.
+//!
+//! This struct stores the max damage of the tower.
+//!
+struct CollatzDamage
+{
+    int maxDamage;
+};
+}  // namespace CubbyTower
+
+#endif  // CUBBYTOWER_COLLATZ_DAMAGE_HPP
\ No newline at end of file
diff --git a/Includes/CubbyTower/Helpers/ShootingHelpers.hpp b/Includes/CubbyTower/Helpers/ShootingHelpers.hpp
index 2afb32b..f1e559e 100644
--- a/Includes/CubbyTower/Helpers/ShootingHelpers.hpp
+++ b/Includes/CubbyTower/Helpers/ShootingHelpers.hpp
@@ -24,6 +24,14 @@ namespace Shooting
 void CreateArrow(entt::registry& registry, const Position& from,
                  const Position& to, int damage);
 
+//! Creates an Collatz entity to shoot a target.
+//! \param registry A registry that handles entities.
+//! \param from The start position of the collatz for the collatz tower.
+//! \param to The end position of the collatz for target.
+//! \param collatzDamage The amount of collatz damage to give.
+void CreateCollatz(entt::registry& registry, const Position& from,
+                   const Position& to, CollatzDamage collatzDamage);
+
 //! Gives a damage to a target.
 //! \param registry A registry that handles entities.
 //! \param target A target that takes a damage.
diff --git a/Includes/CubbyTower/Helpers/TowerHelpers.hpp b/Includes/CubbyTower/Helpers/TowerHelpers.hpp
index bce9a14..ab34583 100644
--- a/Includes/CubbyTower/Helpers/TowerHelpers.hpp
+++ b/Includes/CubbyTower/Helpers/TowerHelpers.hpp
@@ -48,6 +48,18 @@ void ShootArrowLv1(entt::registry& registry, entt::entity target,
 void ShootArrowLv2(entt::registry& registry, entt::entity target,
                    entt::entity from);
 
+//! Buys a collatz tower.
+//! \param registry A registry that handles entities.
+//! \param position The position to place a collatz tower.
+void BuyCollatzTower(entt::registry& registry, const Position& position);
+
+// Shoots a collatz instance for collatz tower.
+//! \param registry A registry that handles entities.
+//! \param target A target entity to shoot.
+//! \param from A tower entity that shoots collatz instance.
+void ShootCollatz(entt::registry& registry, entt::entity target,
+                  entt::entity from);
+
 //! Finds a first target within a range.
 //! \param registry A registry that handles entities.
 //! \return a first target if it is within a range, entt::null otherwise.
diff --git a/Sources/CubbyTower/Game.cpp b/Sources/CubbyTower/Game.cpp
index a5bda5f..8224dce 100644
--- a/Sources/CubbyTower/Game.cpp
+++ b/Sources/CubbyTower/Game.cpp
@@ -137,6 +137,12 @@ void Initialize(entt::registry& registry)
             [](entt::registry& registry, entt::entity button) {
                 Tower::CreatePlacer(registry, Tower::BuyArrowTower);
             });
+
+        UI::CreateTowerButton(
+            registry, "Collatz Tower", { -1, 15.5f }, COLLATZ_TOWER_PRICE,
+            [](entt::registry& registry, entt::entity button) {
+                Tower::CreatePlacer(registry, Tower::BuyCollatzTower);
+            });
     }
 }
 
diff --git a/Sources/CubbyTower/Helpers/ShootingHelpers.cpp b/Sources/CubbyTower/Helpers/ShootingHelpers.cpp
index 4c8b021..7597f1f 100644
--- a/Sources/CubbyTower/Helpers/ShootingHelpers.cpp
+++ b/Sources/CubbyTower/Helpers/ShootingHelpers.cpp
@@ -5,6 +5,7 @@
 // property of any third parties.
 
 #include <CubbyTower/Commons/Tags.hpp>
+#include <CubbyTower/Components/CollatzDamage.hpp>
 #include <CubbyTower/Components/Color.hpp>
 #include <CubbyTower/Components/Damage.hpp>
 #include <CubbyTower/Components/DeathTimer.hpp>
@@ -53,6 +54,48 @@ static void OnCollideArrow(entt::registry& registry, entt::entity entity)
     registry.emplace<Color>(fxEntity, color);
 }
 
+static void OnCollideCollatz(entt::registry& registry, entt::entity entity)
+{
+    auto impactPoint = registry.get<Position>(entity);
+    auto color = registry.get<Color>(entity);
+    auto collatzDamage = registry.get<CollatzDamage>(entity);
+
+    registry.destroy(entity);
+
+    registry.view<Health, Position>().each(
+        [&registry, impactPoint, collatzDamage](
+            entt::entity entity, [[maybe_unused]] const Health& health,
+            const Position& position) {
+            auto dx = position.x - impactPoint.x;
+            auto dy = position.y - impactPoint.y;
+            auto dist = dx * dx + dy * dy;
+
+            if (dist < 0.5f)
+            {
+                int damage = collatzDamage.maxDamage;
+                
+                if (health.curAmount % 2 == 0)
+                {
+                    damage = std::min(damage, health.curAmount / 2);
+                }
+                else
+                {
+                    damage = -(health.curAmount * 2 + 1);
+                }
+                
+                GiveDamage(registry, entity, damage);
+            }
+        });
+
+    auto fxEntity = registry.create();
+    registry.emplace<Position>(fxEntity, impactPoint);
+    registry.emplace<DeathTimer>(fxEntity, 0.4f);
+    registry.emplace<Size>(fxEntity, 0.5f);
+    registry.emplace<ShapeRenderer>(fxEntity, Shape::DrawCircle);
+    registry.emplace<SizePulseAnim>(fxEntity, 0.0f, 25.0f, 0.15f, 0.5f);
+    registry.emplace<Color>(fxEntity, color);
+}
+
 void CreateArrow(entt::registry& registry, const Position& from,
                  const Position& to, int damage)
 {
@@ -70,6 +113,23 @@ void CreateArrow(entt::registry& registry, const Position& from,
     registry.emplace<Damage>(entity, damage);
 }
 
+void CreateCollatz(entt::registry& registry, const Position& from,
+                   const Position& to, CollatzDamage collatzDamage)
+{
+    const float dx = to.x - from.x;
+    const float dy = to.y - from.y;
+    const float len = std::sqrt(dx * dx + dy * dy);
+
+    auto entity = registry.create();
+    registry.emplace<Position>(entity, from);
+    registry.emplace<PositionAnim>(entity, from, to, 0.0f, len / 10.0f,
+                                   OnCollideCollatz);
+    registry.emplace<ShapeRenderer>(entity, Shape::DrawBox);
+    registry.emplace<Size>(entity, 0.15f, 0.15f);
+    registry.emplace<Color>(entity, Color{ 0.0f, 1.0f, 1.0f, 1.0f });
+    registry.emplace<CollatzDamage>(entity, collatzDamage);
+}
+
 void GiveDamage(entt::registry& registry, entt::entity& target, int damage)
 {
     if (!registry.all_of<Health>(target))
@@ -79,6 +139,7 @@ void GiveDamage(entt::registry& registry, entt::entity& target, int damage)
 
     auto& health = registry.get<Health>(target);
     health.curAmount -= damage;
+    health.curAmount = std::min(health.curAmount, health.maxAmount);
 
     if (health.curAmount <= 0)
     {
@@ -92,4 +153,4 @@ void Kill(entt::registry& registry, entt::entity& target)
 
     registry.destroy(target);
 }
-}  // namespace CubbyTower::Shooting
\ No newline at end of file
+}  // namespace CubbyTower::Shooting
diff --git a/Sources/CubbyTower/Helpers/TowerHelpers.cpp b/Sources/CubbyTower/Helpers/TowerHelpers.cpp
index c07e6bd..f1c4b5e 100644
--- a/Sources/CubbyTower/Helpers/TowerHelpers.cpp
+++ b/Sources/CubbyTower/Helpers/TowerHelpers.cpp
@@ -7,6 +7,7 @@
 #include <CubbyTower/Commons/Constants.hpp>
 #include <CubbyTower/Commons/Tags.hpp>
 #include <CubbyTower/Commons/TowerData.hpp>
+#include <CubbyTower/Components/CollatzDamage.hpp>
 #include <CubbyTower/Components/Color.hpp>
 #include <CubbyTower/Components/FindTarget.hpp>
 #include <CubbyTower/Components/Hoverable.hpp>
@@ -91,6 +92,39 @@ void ShootArrowLv2(entt::registry& registry, entt::entity target,
     // Do nothing
 }
 
+void BuyCollatzTower(entt::registry& registry, const Position& position)
+{
+    // Check the player can buy arrow tower
+    if (!Bank::Withdraw(registry, registry.view<Tag::Player>()[0],
+                        COLLATZ_TOWER_PRICE))
+    {
+        return;
+    }
+
+    auto entity = registry.create();
+    registry.emplace<Tag::Tower>(entity);
+    registry.emplace<Position>(entity, position);
+    registry.emplace<Size>(entity, TOWER_SIZE, TOWER_SIZE);
+    registry.emplace<Color>(entity, TOWER_LEVEL1_COLOR);
+    registry.emplace<TextRenderer>(entity, "C", Color{ 0.0f, 0.0f, 0.0f, 0.0f },
+                                   0.5f);
+    registry.emplace<ShapeRenderer>(entity, Shape::DrawBox);
+    registry.emplace<Name>(entity, "Collatz Tower(WIP)");
+    registry.emplace<Targeter>(entity, TargetMask{ GROUND | AIR },
+                               210.0f / 60.0f, 1.0f, ShootCollatz);
+    registry.emplace<Hoverable>(entity);
+    registry.emplace<FindTarget>(entity, FindFirstTarget);
+}
+
+void ShootCollatz(entt::registry& registry, entt::entity target,
+                  entt::entity from)
+{
+    Shooting::CreateCollatz(registry, registry.get<Position>(from),
+                            registry.get<Position>(target),
+                            CollatzDamage{ 100 });
+    Audio::PlaySound("arrow");
+}
+
 entt::entity FindFirstTarget(entt::registry& registry)
 {
     return entt::null;