diff --git a/code/__HELPERS/unsorted.dm b/code/__HELPERS/unsorted.dm
index 4bbc7d03d07..8b4cea27947 100644
--- a/code/__HELPERS/unsorted.dm
+++ b/code/__HELPERS/unsorted.dm
@@ -1926,24 +1926,6 @@ GLOBAL_DATUM_INIT(dview_mob, /mob/dview, new)
 
 	return pois
 
-/proc/flash_color(mob_or_client, flash_color="#960000", flash_time=20)
-	var/client/C
-	if(istype(mob_or_client, /mob))
-		var/mob/M = mob_or_client
-		if(M.client)
-			C = M.client
-		else
-			return
-	else if(istype(mob_or_client, /client))
-		C = mob_or_client
-
-	if(!istype(C))
-		return
-
-	C.color = flash_color
-	spawn(0)
-		animate(C, color = initial(C.color), time = flash_time)
-
 #define RANDOM_COLOUR (rgb(rand(0,255),rand(0,255),rand(0,255)))
 
 /proc/make_bit_triplet()
diff --git a/code/modules/mob/living/simple_animal/hostile/megafauna/colossus.dm b/code/modules/mob/living/simple_animal/hostile/megafauna/colossus.dm
index 6324e8bb7a6..c0dcff97bb9 100644
--- a/code/modules/mob/living/simple_animal/hostile/megafauna/colossus.dm
+++ b/code/modules/mob/living/simple_animal/hostile/megafauna/colossus.dm
@@ -205,10 +205,9 @@ Difficulty: Very Hard
 		shoot_projectile(E)
 
 /mob/living/simple_animal/hostile/megafauna/colossus/proc/telegraph()
-	for(var/mob/M in range(10,src))
-		if(M.client)
-			flash_color(M.client, "#C80000", 1)
-			shake_camera(M, 4, 3)
+	for(var/mob/M in range(10, src))
+		M.flash_screen_color("#C80000", 1)
+		shake_camera(M, 4, 3)
 	playsound(src, 'sound/magic/narsie_attack.ogg', 200, TRUE)
 
 
diff --git a/code/modules/mob/living/simple_animal/hostile/megafauna/hierophant.dm b/code/modules/mob/living/simple_animal/hostile/megafauna/hierophant.dm
index c83cf6c3c18..e7fe3f53632 100644
--- a/code/modules/mob/living/simple_animal/hostile/megafauna/hierophant.dm
+++ b/code/modules/mob/living/simple_animal/hostile/megafauna/hierophant.dm
@@ -670,8 +670,7 @@ Difficulty: Hard
 		hit_things += L
 		if((friendly_fire_check && caster && caster.faction_check_mob(L)) || L.stat == DEAD)
 			continue
-		if(L.client)
-			flash_color(L.client, "#660099", 1)
+		L.flash_screen_color("#660099", 1)
 		playsound(L,'sound/weapons/sear.ogg', 50, TRUE, -4)
 		to_chat(L, "<span class='userdanger'>You're struck by a [name]!</span>")
 		var/limb_to_hit = L.get_organ(pick(BODY_ZONE_HEAD, BODY_ZONE_CHEST, BODY_ZONE_R_ARM, BODY_ZONE_L_ARM, BODY_ZONE_R_LEG, BODY_ZONE_L_LEG))
diff --git a/code/modules/mob/mob_helpers.dm b/code/modules/mob/mob_helpers.dm
index 8276d06f126..38669dba55f 100644
--- a/code/modules/mob/mob_helpers.dm
+++ b/code/modules/mob/mob_helpers.dm
@@ -13,6 +13,7 @@
 	return 0
 
 /mob/proc/get_screen_colour()
+	return
 
 /mob/proc/update_client_colour(time = 10) //Update the mob's client.color with an animation the specified time in length.
 	if(!client) //No client_colour without client. If the player logs back in they'll be back through here anyway.
@@ -31,6 +32,19 @@
 	else if(eyes) //If they're not, check to see if their eyes got one of them there colour matrices. Will be null if eyes are robotic/the mob isn't colourblind and they have no default colour matrix.
 		return eyes.get_colourmatrix()
 
+/**
+  * Flash up a color as an overlay on a player's screen, then fade back to normal.
+  *
+  * Arguments:
+  * * flash_color - The color to overlay on the screen.
+  * * flash_time - The time it takes for the color to fade back to normal.
+  */
+/mob/proc/flash_screen_color(flash_color, flash_time)
+	if(!client)
+		return
+	client.color = flash_color
+	INVOKE_ASYNC(client, /client/.proc/colour_transition, get_screen_colour(), flash_time)
+
 /proc/ismindshielded(A) //Checks to see if the person contains a mindshield implant, then checks that the implant is actually inside of them
 	for(var/obj/item/implant/mindshield/L in A)
 		if(L && L.implanted)
diff --git a/code/modules/ruins/objects_and_mobs/necropolis_gate.dm b/code/modules/ruins/objects_and_mobs/necropolis_gate.dm
index d5f7a1e1aa2..2277e096a30 100644
--- a/code/modules/ruins/objects_and_mobs/necropolis_gate.dm
+++ b/code/modules/ruins/objects_and_mobs/necropolis_gate.dm
@@ -182,10 +182,10 @@ GLOBAL_DATUM(necropolis_gate, /obj/structure/necropolis_gate/legion_gate)
 
 		var/sound/legion_sound = sound('sound/creatures/legion_spawn.ogg')
 		for(var/mob/M in GLOB.player_list)
-			if(M.z == z)
+			if(M.z == z && M.client)
 				to_chat(M, "<span class='userdanger'>Discordant whispers flood your mind in a thousand voices. Each one speaks your name, over and over. Something horrible has been released.</span>")
 				M.playsound_local(T, null, 100, FALSE, 0, FALSE, pressure_affected = FALSE, S = legion_sound)
-				flash_color(M, flash_color = "#FF0000", flash_time = 50)
+				M.flash_screen_color("#FF0000", 5 SECONDS)
 		var/mutable_appearance/release_overlay = mutable_appearance('icons/effects/effects.dmi', "legiondoor")
 		notify_ghosts("Legion has been released in the [get_area(src)]!", source = src, alert_overlay = release_overlay, action = NOTIFY_JUMP)