diff --git a/zone/command.cpp b/zone/command.cpp
index 35b920e53..1df75a9ca 100644
--- a/zone/command.cpp
+++ b/zone/command.cpp
@@ -225,6 +225,7 @@ int command_init(void)
 		command_add("suspend", "[name] [days] [reason] - Suspend by character name and for specificed number of days", AccountStatus::GMLeadAdmin, command_suspend) ||
 		command_add("suspendmulti", "[Character Name One|Character Name Two|etc] [Days] [Reason] - Suspend multiple characters by name for specified number of days", AccountStatus::GMLeadAdmin, command_suspendmulti) ||
 		command_add("takeplatinum", "[Platinum] - Takes specified amount of platinum from you or your player target", AccountStatus::GMMgmt, command_takeplatinum) ||
+		command_add("test", "Test Command", AccountStatus::GMLeadAdmin, command_test) ||
 		command_add("task", "(subcommand) - Task system commands", AccountStatus::GMLeadAdmin, command_task) ||
 		command_add("petname", "[newname] - Temporarily renames your pet. Leave name blank to restore the original name.", AccountStatus::GMAdmin, command_petname) ||
 		command_add("traindisc", "[level] - Trains all the disciplines usable by the target, up to level specified. (may freeze client for a few seconds)", AccountStatus::GMLeadAdmin, command_traindisc) ||
@@ -920,6 +921,7 @@ void command_bot(Client *c, const Seperator *sep)
 #include "gm_commands/suspend.cpp"
 #include "gm_commands/suspendmulti.cpp"
 #include "gm_commands/takeplatinum.cpp"
+#include "gm_commands/test.cpp"
 #include "gm_commands/task.cpp"
 #include "gm_commands/traindisc.cpp"
 #include "gm_commands/tune.cpp"
diff --git a/zone/command.h b/zone/command.h
index 09164e6bf..0b78b555e 100644
--- a/zone/command.h
+++ b/zone/command.h
@@ -179,6 +179,7 @@ void command_summonitem(Client *c, const Seperator *sep);
 void command_suspend(Client *c, const Seperator *sep);
 void command_suspendmulti(Client *c, const Seperator *sep);
 void command_takeplatinum(Client* c, const Seperator* sep);
+void command_test(Client *c, const Seperator *sep);
 void command_task(Client *c, const Seperator *sep);
 void command_petname(Client *c, const Seperator *sep);
 void command_traindisc(Client *c, const Seperator *sep);
diff --git a/zone/entity.cpp b/zone/entity.cpp
index fab1be99f..2d1cdeaba 100644
--- a/zone/entity.cpp
+++ b/zone/entity.cpp
@@ -2941,7 +2941,7 @@ void EntityList::ScanCloseMobs(Mob *scanning_mob)
 		return;
 	}
 
-	float scan_range = RuleI(Range, MobCloseScanDistance) * RuleI(Range, MobCloseScanDistance);
+	float scan_range = zone->GetMaxUpdateRange();
 
 	// Reserve memory in m_close_mobs to avoid frequent re-allocations if not already reserved.
 	// Assuming mob_list.size() as an upper bound for reservation.
@@ -2957,7 +2957,7 @@ void EntityList::ScanCloseMobs(Mob *scanning_mob)
 			continue;
 		}
 
-		float distance = DistanceSquared(scanning_mob->GetPosition(), mob->GetPosition());
+		float distance = Distance(scanning_mob->GetPosition(), mob->GetPosition());
 		if (distance <= scan_range || mob->GetAggroRange() >= scan_range) {
 			// add mob to scanning_mob's close list and vice versa
 			// check if the mob is already in the close mobs list before inserting
@@ -2968,6 +2968,8 @@ void EntityList::ScanCloseMobs(Mob *scanning_mob)
 		}
 	}
 
+	UpdateVisibility(scanning_mob);
+
 	LogAIScanClose(
 		"[{}] Scanning close list > list_size [{}] moving [{}]",
 		scanning_mob->GetCleanName(),
@@ -2976,6 +2978,97 @@ void EntityList::ScanCloseMobs(Mob *scanning_mob)
 	);
 }
 
+void EntityList::UpdateVisibility(Mob *scanning_mob)
+{
+	if (!scanning_mob || !scanning_mob->IsClient()) {
+		return;
+	}
+
+	// Ensure sufficient capacity in the visibility map
+	if (scanning_mob->m_can_see_mob.bucket_count() < scanning_mob->m_close_mobs.size()) {
+		scanning_mob->m_can_see_mob.reserve(scanning_mob->m_close_mobs.size());
+	}
+
+	// Update visibility for all mobs in the close list of `scanning_mob`
+	for (auto &e : scanning_mob->m_close_mobs) {
+		auto mob = e.second;
+		if (!mob) continue;
+
+		int mob_id = mob->GetID();
+
+		// Update visibility for `scanning_mob` to `mob`
+		auto [it_scanning_visible, inserted_scanning_visible] = scanning_mob->m_can_see_mob.try_emplace(mob_id, false);
+		bool scanning_last_known_visible = it_scanning_visible->second;
+
+		if (!scanning_last_known_visible) {
+			scanning_mob->SendAppearancePacket(
+				AppearanceType::Invisibility,
+				0,
+				false,
+				true,
+				mob->CastToClient()
+			);
+			it_scanning_visible->second = true;
+			scanning_mob->Shout(fmt::format("Setting scanning_mob visible to mob [{}]", mob->GetCleanName()).c_str());
+		}
+
+		// Now update the visibility for `mob` to `scanning_mob`
+		auto [it_mob_visible, inserted_mob_visible] = mob->m_can_see_mob.try_emplace(scanning_mob->GetID(), false);
+		bool mob_last_known_visible = it_mob_visible->second;
+
+		if (!mob_last_known_visible) {
+			mob->SendAppearancePacket(
+				AppearanceType::Invisibility,
+				0,
+				false,
+				true,
+				scanning_mob->CastToClient()
+			);
+			it_mob_visible->second = true;
+			mob->Shout(fmt::format("Setting mob visible to scanning_mob [{}]", scanning_mob->GetCleanName()).c_str());
+		}
+	}
+
+	// Check all other mobs to make invisible if they are no longer close
+	for (auto &e : mob_list) {
+		auto mob = e.second;
+		if (!mob) continue;
+
+		int mob_id = mob->GetID();
+		bool is_on_close_list = mob->m_close_mobs.find(scanning_mob->GetID()) != mob->m_close_mobs.end();
+
+		// Update scanning_mob's view of mob visibility
+		auto [it, inserted] = scanning_mob->m_can_see_mob.try_emplace(mob_id, false);
+		bool last_known_visible = it->second;
+
+		if (!is_on_close_list && last_known_visible) {
+			scanning_mob->SendAppearancePacket(
+				AppearanceType::Invisibility,
+				3001,
+				false,
+				true,
+				mob->CastToClient()
+			);
+			it->second = false;
+			scanning_mob->Shout(fmt::format("Setting mob [{}] invisible to scanning_mob", mob->GetCleanName()).c_str());
+		}
+
+		// Inverse: Update mob's view of scanning_mob visibility
+		auto it_mob = mob->m_can_see_mob.find(scanning_mob->GetID());
+		if (it_mob != mob->m_can_see_mob.end() && !scanning_mob->m_close_mobs.count(mob_id) && it_mob->second) {
+			mob->SendAppearancePacket(
+				AppearanceType::Invisibility,
+				3001,
+				false,
+				true,
+				scanning_mob->CastToClient()
+			);
+			it_mob->second = false;
+			mob->Shout(fmt::format("Setting scanning_mob [{}] invisible to mob", scanning_mob->GetCleanName()).c_str());
+		}
+	}
+}
+
 bool EntityList::RemoveMerc(uint16 delete_id)
 {
 	auto it = merc_list.find(delete_id);
diff --git a/zone/entity.h b/zone/entity.h
index 33313f14e..f52ae8c3c 100644
--- a/zone/entity.h
+++ b/zone/entity.h
@@ -570,6 +570,7 @@ public:
 	void RefreshClientXTargets(Client *c);
 	void SendAlternateAdvancementStats();
 	void ScanCloseMobs(Mob *scanning_mob);
+	void UpdateVisibility(Mob *scanning_mob);
 
 	void GetTrapInfo(Client* c);
 	bool IsTrapGroupSpawned(uint32 trap_id, uint8 group);
diff --git a/zone/gm_commands/test.cpp b/zone/gm_commands/test.cpp
new file mode 100755
index 000000000..c8ebc5e8f
--- /dev/null
+++ b/zone/gm_commands/test.cpp
@@ -0,0 +1,14 @@
+
+void command_test(Client *c, const Seperator *sep)
+{
+	const int arguments = sep->argnum;
+
+	for (auto &e : entity_list.GetMobList()) {
+		auto mob = e.second;
+		if (Distance(c->GetPosition(), mob->GetPosition()) > 100) {
+			mob->SendAppearancePacket(AppearanceType::Invisibility, 3001);
+		} else {
+			mob->SendAppearancePacket(AppearanceType::Invisibility, 0);
+		}
+	}
+}
diff --git a/zone/mob.h b/zone/mob.h
index 297aa80cb..1bdcac89b 100644
--- a/zone/mob.h
+++ b/zone/mob.h
@@ -202,6 +202,7 @@ public:
 	void DisplayInfo(Mob *mob);
 
 	std::unordered_map<uint16, Mob *> m_close_mobs;
+	std::unordered_map<int, bool>     m_can_see_mob;
 	Timer                             m_scan_close_mobs_timer;
 	Timer                             m_mob_check_moving_timer;
 
diff --git a/zone/zone.cpp b/zone/zone.cpp
index f02be2e2b..cc78a907f 100644
--- a/zone/zone.cpp
+++ b/zone/zone.cpp
@@ -2780,7 +2780,7 @@ void Zone::CalculateNpcUpdateDistanceSpread()
 	int x_spread        = int(std::abs(max_x - min_x));
 	int y_spread        = int(std::abs(max_y - min_y));
 	int combined_spread = int(std::abs((x_spread + y_spread) / 2));
-	int update_distance = EQ::ClampLower(int(combined_spread / 4), int(zone->GetMaxMovementUpdateRange()));
+	int update_distance = EQ::ClampLower(int(combined_spread / 4), int(zone->GetMaxUpdateRange()));
 
 	SetNpcPositionUpdateDistance(update_distance);
 
diff --git a/zone/zone.h b/zone/zone.h
index c29a89b29..a86987f1f 100755
--- a/zone/zone.h
+++ b/zone/zone.h
@@ -417,7 +417,7 @@ public:
 		SendDiscordMessage(webhook_id, message_prefix + Discord::FormatDiscordMessage(log_category, message));
 	};
 
-	double GetMaxMovementUpdateRange() const { return max_movement_update_range; }
+	double GetMaxUpdateRange() const { return max_movement_update_range; }
 
 	void SetIsHotzone(bool is_hotzone);