diff --git a/code/game/objects/items/explosives/grenades/marines.dm b/code/game/objects/items/explosives/grenades/marines.dm
index 326c5efdb0ff..aee78b96fbbd 100644
--- a/code/game/objects/items/explosives/grenades/marines.dm
+++ b/code/game/objects/items/explosives/grenades/marines.dm
@@ -749,12 +749,16 @@
 
 	if(target != get_turf(user))
 		return
-
+	user.visible_message(SPAN_NOTICE("[user] starts deploying [src]."), \
+		SPAN_NOTICE("You start deploying [src]."))
 	to_chat(user, SPAN_NOTICE("You switch [src] into landmine mode and start placing it..."))
 	playsound(user.loc, 'sound/effects/thud.ogg', 100, 6)
 	if(!do_after(user,2 SECONDS * user.get_skill_duration_multiplier(SKILL_CONSTRUCTION), INTERRUPT_ALL|BEHAVIOR_IMMOBILE, BUSY_ICON_BUILD))
 		to_chat(user, SPAN_NOTICE("You stop digging."))
 		return
+
+	user.visible_message(SPAN_NOTICE("[user] finishes deploying [src]."), \
+		SPAN_NOTICE("You finish deploying [src]."))
 	var/obj/item/explosive/mine/sebb/planted = new /obj/item/explosive/mine/sebb(get_turf(user))
 	planted.pixel_x += rand(-5,5)
 	planted.pixel_y += rand(-5,5)
@@ -767,33 +771,42 @@
 
 
 /obj/item/explosive/grenade/sebb/prime()
+	var/datum/effect_system/spark_spread/spark = new /datum/effect_system/spark_spread
 	var/list/full_range = oview(range,src) // Fill a list of stuff in the range so we won't have to spam it
 	new /obj/effect/overlay/sebb(get_turf(src))
 	playsound(src.loc, 'sound/effects/sebb_explode.ogg', 100, 0, 10)
 	create_shrapnel(loc, spark_count/2, , ,/datum/ammo/bullet/shrapnel/light/effect/ver1, cause_data)
 	create_shrapnel(loc, spark_count/2, , ,/datum/ammo/bullet/shrapnel/light/effect/ver2, cause_data)
-
+	for(var/obj/structure/machinery/defenses/sentry/sentry_stun in full_range)
+		sentry_stun.sentry_range = 0 // Temporarily "disable" the sentry by killing its range then setting it back.
+
+		addtimer(VARSET_CALLBACK(sentry_stun, sentry_range, initial(sentry_stun.sentry_range)), 2 SECONDS)
+		sentry_stun.visible_message(SPAN_DANGER("[src]'s screen flickes violently as it's shocked!"))
+		sentry_stun.visible_message(SPAN_DANGER("[src] says \"ERROR: Fire control system resetting due to critical voltage flucuation!\""))
+		spark.set_up(5, 1, sentry_stun)
+		spark.start()
 	for(var/turf/turf in full_range)
 		if(prob(25))
-			var/datum/effect_system/spark_spread/spark = new /datum/effect_system/spark_spread
 			spark.set_up(2, 1, turf)
 			spark.start()
 	for(var/mob/living/mob in full_range)
 		var/mob_range = get_dist(src,mob)
-		to_chat(world,mob_range)  /// REMOVETHIS REMOVETHIS
 		var/dam_factor = mob_range * dam_range_mult
-		to_chat(world,dam_factor)  /// REMOVETHIS REMOVETHIS
 		var/damage_applied = damage - dam_factor  //divides damage
 		if(ishuman(mob))
 			var/mob/living/carbon/human/shocked_human = mob
+			if(shocked_human.species == /datum/species/synthetic) // Massive overvoltage to ungrounded robots is pretty bad
+				damage_applied = damage_applied * 2
+				spark.set_up(5, 1, shocked_human)
+				spark.start()
+				shocked_human.Stun(1)
+				to_chat(mob,SPAN_HIGHDANGER("All of your systems jam up as your main bus is overvolted by [damage_applied*2] volts."))
 			shocked_human.take_overall_armored_damage(damage_applied ,ARMOR_ENERGY,BURN, 90) // 90% chance to be on additional limbs
 			shocked_human.make_dizzy(damage_applied*3)
 			shocked_human.make_jittery(damage_applied*3)
 			shocked_human.emote("pain")
 		else
 			mob.apply_damage(damage_applied, BURN)
-		//mob.KnockDown(5)  /// REMOVETHIS REMOVETHIS
-		if(!(mob.client))	continue // REMOVETHIS REMOVETHIS anticrash
 		if(mob_range < 1) // they are probably dead if human so no unique human stuff.
 			mob.KnockDown(2)
 			mob.Superslow(3)