diff --git a/descriptions/ab+/en_us.lua b/descriptions/ab+/en_us.lua
index 8518d910..4b3fc959 100644
--- a/descriptions/ab+/en_us.lua
+++ b/descriptions/ab+/en_us.lua
@@ -977,3 +977,14 @@ EID.descriptions[languageCode].ConditionalDescs = {
 	["5.300.15"] = "{{DemonBeggar}} Spawns a Devil Beggar", -- Temperance (Greed Mode effect)
 	["5.350.23"] = "{{Warning}} Dying in a {{SacrificeRoom}} Sacrifice Room while holding this trinket unlocks The Lost", -- Missing Poster (Unlock The Lost)
 }
+
+EID.descriptions[languageCode].BFFSSynergies = {
+	["NoEffect"] = "No Effect",
+	["DoubleDamage"] = "Damage doubled",
+	["5.100.273"] = "Doubles impact damage and increases explosive damage by 25", -- Bob's Brain
+	["5.100.266"] = "Spawns an extra Blue Spider", -- Juicy Sack
+	["5.100.360"] = "Shoots tears that deal 200% of your damage", -- Incubus
+	["5.100.417"] = "Increases radius, but not damage", -- Succubus
+	["5.100.537"] = "Increases pool size, but not damage", -- Lil Spewer
+	["5.100.539"] = "Spawns a champion variant of the enemy", -- Mystery Egg
+}
diff --git a/descriptions/rep/en_us.lua b/descriptions/rep/en_us.lua
index e9f0423b..45e9b705 100644
--- a/descriptions/rep/en_us.lua
+++ b/descriptions/rep/en_us.lua
@@ -1201,6 +1201,16 @@ local repConditions={
 }
 EID:updateDescriptionsViaTable(repConditions, EID.descriptions[languageCode].ConditionalDescs)
 
+local repBFFSSynergies = {
+	["5.100.360"] = "Shoots tears that deal 150% of your damage. 200% for Lilith", -- Incubus
+	["5.100.610"] = "Spawns 4 rock waves in an x pattern. Doubles bird damage. Damage of waves unaffected.", -- Bird Cage
+	["5.100.569"] = "+2 full hearts when health is drained", -- Blood Oath
+	["5.100.178"] = "Double water damage and spawns a blue flame at point of impact", -- Holy Water
+	["5.100.276"] = "Fires additional shots in random directions and leaves a larger puddle of creep", -- Isaac's Heart
+	["5.100.612"] = "Gives the Lost Soul a Holy Mantle effect", -- Lost Soul
+	["5.100.635"] = "On use, fires 8 tears from the players position that have the same effects as his tears", -- Stitches
+}
+EID:updateDescriptionsViaTable(repBFFSSynergies, EID.descriptions[languageCode].BFFSSynergies)
 
 -- If Debug enabled, add overwrite tables to the languagepack in order for the language completion script to be able to compare them
 if EID.enableDebug then
diff --git a/eid_data.lua b/eid_data.lua
index fde9e782..23de284a 100644
--- a/eid_data.lua
+++ b/eid_data.lua
@@ -900,7 +900,10 @@ EID.ItemPoolTypeToMarkup = { [0] = "{{ItemPoolTreasure}}", "{{ItemPoolShop}}", "
 EID.LocalModePositionOffset = {
 	Default = Vector(0, 20),
 	Shop = function(entity) if EID:EntitySanityCheck(entity) and not EID:IsGridEntity(entity) and entity:ToPickup() and entity:ToPickup():IsShopItem() then return Vector(0, 35) end end,
-} 
+}
+
+-- Items that dont have an effect with BFFS! item
+EID.BFFSNoSynergy = {[11] = true, [81] = true, [238] = true, [239] = true, [243] = true,  [265] = true, [268] = true, [269] = true, [278] = true, [280] = true, [281] = true, [387] = true, [404] = true, [405] = true, [431] = true, [436] = true, [469] = true, [472] = true, [492] = true, [516] = true, [528] = true, [542] = true, [543] = true }
 
 -- Character IDs that aren't allowed to have Red Health: ???, The Lost, The Soul
 EID.NoRedHeartsPlayerIDs = { [4] = true, [10] = true, [17] = true }
@@ -908,3 +911,10 @@ if REPENTANCE then
 	-- ???, The Lost, Black Judas, The Soul, Tainted Judas, Tainted ???, Tainted Lost, Tainted Forgotten, Tainted Bethany, Tainted Soul
 	EID.NoRedHeartsPlayerIDs = { [4] = true, [10] = true, [12] = true, [17] = true, [24] = true, [25] = true, [31] = true, [35] = true, [36] = true, [40] = true }
 end
+
+if REPENTANCE then
+	EID.BFFSNoSynergy[504] = true -- Brown Nugget
+	EID.BFFSNoSynergy[567] = true -- Paschal Candle
+	EID.BFFSNoSynergy[651] = true -- Star of Bethlehem
+	EID.BFFSNoSynergy[697] = true -- Vanishing Twin
+end
\ No newline at end of file
diff --git a/eid_modifiers.lua b/eid_modifiers.lua
index 691369fe..6178bf48 100644
--- a/eid_modifiers.lua
+++ b/eid_modifiers.lua
@@ -7,7 +7,7 @@ EID.inModifierPreview = false
 EID.TabDescThisFrame = false
 
 -- List of collectible IDs for us to check if a player owns them; feel free to add to this in mods that add description modifiers!
-EID.collectiblesToCheck = { CollectibleType.COLLECTIBLE_VOID, CollectibleType.COLLECTIBLE_CAR_BATTERY }
+EID.collectiblesToCheck = { CollectibleType.COLLECTIBLE_VOID, CollectibleType.COLLECTIBLE_CAR_BATTERY, CollectibleType.COLLECTIBLE_BFFS }
 local maxSlot = 1
 -- Repentance modifiers
 if EID.isRepentance then
@@ -17,7 +17,8 @@ if EID.isRepentance then
 		CollectibleType.COLLECTIBLE_BINGE_EATER, CollectibleType.COLLECTIBLE_BOOK_OF_VIRTUES, CollectibleType.COLLECTIBLE_SPINDOWN_DICE,
 		CollectibleType.COLLECTIBLE_TAROT_CLOTH, CollectibleType.COLLECTIBLE_MOMS_BOX, 59, --Birthright Belial
 		CollectibleType.COLLECTIBLE_BLANK_CARD, CollectibleType.COLLECTIBLE_CLEAR_RUNE, CollectibleType.COLLECTIBLE_PLACEBO,
-		CollectibleType.COLLECTIBLE_FALSE_PHD, CollectibleType.COLLECTIBLE_ABYSS, CollectibleType.COLLECTIBLE_FLIP, CollectibleType.COLLECTIBLE_CAR_BATTERY, CollectibleType.COLLECTIBLE_GLOWING_HOUR_GLASS,
+		CollectibleType.COLLECTIBLE_FALSE_PHD, CollectibleType.COLLECTIBLE_ABYSS, CollectibleType.COLLECTIBLE_FLIP, CollectibleType.COLLECTIBLE_CAR_BATTERY, 
+		CollectibleType.COLLECTIBLE_GLOWING_HOUR_GLASS, CollectibleType.COLLECTIBLE_BFFS
 	}
 end
 EID.collectiblesOwned = {}
@@ -290,6 +291,18 @@ local function BlackFeatherCallback(descObj)
 	return descObj
 end
 
+local function BFFSSynergiesCallback(descObj)
+	local description = EID:getDescriptionEntry("BFFSSynergies", descObj.fullItemString, true)
+	if EID.BFFSNoSynergy[descObj.ObjSubType] then
+		description = EID:getDescriptionEntry("BFFSSynergies", "NoEffect")
+	elseif description == nil then
+		description = EID:getDescriptionEntry("BFFSSynergies", "DoubleDamage")
+	end
+
+	EID:appendToDescription(descObj, "#{{Collectible247}} {{ColorOrange}}" .. description .. "{{CR}}")
+	return descObj
+end
+
 if EID.isRepentance then
 	-- Handle Birthright
 	local function BirthrightCallback(descObj)
@@ -914,6 +927,14 @@ local function EIDConditionsAB(descObj)
 			if EID.blackRuneOwned then table.insert(callbacks, BlackRuneCallback) end
 		end
 		if EID.collectiblesOwned[356] then table.insert(callbacks, CarBatteryCallback) end
+
+		-- BFF Synergy check
+		if EID.collectiblesOwned[247] then
+			local config = EID.itemConfig:GetCollectible(descObj.ObjSubType)
+			if config ~= nil and config.Type == ItemType.ITEM_FAMILIAR then
+				table.insert(callbacks, BFFSSynergiesCallback)
+			end
+		end
 	elseif descObj.ObjVariant == PickupVariant.PICKUP_TRINKET then
 		if descObj.ObjSubType == 80 then table.insert(callbacks, BlackFeatherCallback) end
 	end