diff --git a/modular_ss220/events/_events.dme b/modular_ss220/events/_events.dme
index f2d0c0781a56..f7491fa48fb4 100644
--- a/modular_ss220/events/_events.dme
+++ b/modular_ss220/events/_events.dme
@@ -4,3 +4,4 @@
 #include "code/headcrabs.dm"
 #include "code/infestation_extended.dm"
 #include "code/christmas.dm"
+#include "code/spider_terror.dm"
diff --git a/modular_ss220/events/code/spider_terror.dm b/modular_ss220/events/code/spider_terror.dm
new file mode 100644
index 000000000000..689c735dc18b
--- /dev/null
+++ b/modular_ss220/events/code/spider_terror.dm
@@ -0,0 +1,111 @@
+#define TS_POINTS_GREEN 9
+#define TS_POINTS_WHITE 17
+#define TS_POINTS_PRINCESS 19
+#define TS_POINTS_PRINCE 30
+#define TS_POINTS_QUEEN 42
+
+
+/datum/event/spider_terror
+	announceWhen = 240
+	var/population_factor = 0.7 // higher - more spawnpoints
+	spawncount = 0 // amount of spawned spiders
+	var/spawnpoints = TS_POINTS_GREEN // weight points
+	/// lists for matching spiders and their weights
+
+	var/list/spider_types = list(
+		"TERROR_GREEN" = /mob/living/simple_animal/hostile/poison/terror_spider/green,
+		"TERROR_WHITE" = /mob/living/simple_animal/hostile/poison/terror_spider/white,
+		"TERROR_PRINCESS" = /mob/living/simple_animal/hostile/poison/terror_spider/queen/princess,
+		"TERROR_PRINCE" = /mob/living/simple_animal/hostile/poison/terror_spider/prince,
+		"TERROR_QUEEN" = /mob/living/simple_animal/hostile/poison/terror_spider/queen
+	)
+
+	var/list/spider_costs = list(
+		"TERROR_GREEN" = TS_POINTS_GREEN,
+		"TERROR_WHITE" = TS_POINTS_WHITE,
+		"TERROR_PRINCESS" = TS_POINTS_PRINCESS,
+		"TERROR_PRINCE" = TS_POINTS_PRINCE,
+		"TERROR_QUEEN" = TS_POINTS_QUEEN
+	)
+
+	var/list/spider_counts = list(
+		"TERROR_GREEN" = 0,
+		"TERROR_WHITE" = 0,
+		"TERROR_PRINCESS" = 0,
+		"TERROR_PRINCE" = 0,
+		"TERROR_QUEEN" = 0
+	)
+
+/datum/event/spider_terror/start()
+	spawncount = 0 // yeah, still not 0
+	// It is necessary to wrap this to avoid the event triggering repeatedly.
+	INVOKE_ASYNC(src, PROC_REF(wrappedstart_new))
+
+/datum/event/spider_terror/proc/wrappedstart_new()
+	var/list/candidates = SSghost_spawns.poll_candidates("Do you want to play as a terror spider?", null, TRUE, source = /mob/living/simple_animal/hostile/poison/terror_spider) // questionable
+	var/max_spiders = length(candidates)
+	log_debug("where is [max_spiders] candidates")
+	spawnpoints += round(population_factor * length(GLOB.clients)) // server population sensitivity
+	log_debug("where is [spawnpoints] available spawnpoints")
+	spawn_terror_spiders(count_spawn_spiders(max_spiders), candidates)
+	SSevents.biohazards_this_round += 1
+
+/datum/event/spider_terror/proc/count_spawn_spiders(max_spiders)
+	while(spawnpoints >= TS_POINTS_GREEN && spawncount < max_spiders)
+		var/chosen_spider_id = pick(spider_costs) // random spider type choose
+		var/cost = spider_costs[chosen_spider_id]
+
+		if(spawnpoints - cost >= 0)
+			spider_counts[chosen_spider_id] += 1
+			spawnpoints -= cost
+			spawncount += 1
+			log_debug("spider added into pool: [chosen_spider_id]")
+			log_debug("where is [spawnpoints] available spawnpoints now")
+
+		if(spawnpoints < TS_POINTS_GREEN || spawncount >= max_spiders)
+			break
+
+	log_debug("selected [spawncount] spider(s)")
+	return spider_counts
+
+/datum/event/spider_terror/proc/spawn_terror_spiders(list/spider_counts, candidates)
+	log_debug("begin spiders spawning")
+	var/list/vents = get_valid_vent_spawns(exclude_mobs_nearby = TRUE)
+	if(!length(vents))
+		message_admins("Warning: No suitable vents detected for spawning terrors. Force picking from station vents regardless of state!")
+		vents = get_valid_vent_spawns(unwelded_only = FALSE, min_network_size = 0)
+
+	log_debug("where is awailible [length(vents)] vents")
+	log_debug("spawncount is:  [spawncount] vents")
+	while(spawncount && length(vents) && length(candidates))
+		for(var/spider_id in spider_counts)
+			var/spider_type = spider_types[spider_id]
+			var/spider_count = spider_counts[spider_id]
+			log_debug("entering inner while cycle")
+			while(spider_count > 0 && length(candidates))
+				var/obj/vent = pick_n_take(vents)
+				var/mob/living/simple_animal/hostile/poison/terror_spider/S = new spider_type(vent.loc)
+				var/mob/M = pick_n_take(candidates)
+				S.key = M.key
+				dust_if_respawnable(M)
+				S.forceMove(vent)
+				S.add_ventcrawl(vent)
+				SEND_SOUND(S, sound('sound/ambience/antag/terrorspider.ogg'))
+				S.give_intro_text()
+				spawncount--
+				successSpawn = TRUE
+
+				spider_count--
+
+			if(spawncount <= 0)
+				break
+
+			spider_counts[spider_type] = 0
+
+	log_and_message_admins("spiders spawned successfully")
+
+#undef TS_POINTS_GREEN
+#undef TS_POINTS_WHITE
+#undef TS_POINTS_PRINCESS
+#undef TS_POINTS_PRINCE
+#undef TS_POINTS_QUEEN