diff --git a/main.lua b/main.lua
index 083f2c0..d78da90 100644
--- a/main.lua
+++ b/main.lua
@@ -13,6 +13,7 @@ end
 
 local data = assert(SMODS.load_file('synergies.lua'))()
 JCA.db = data.jokers
+JCA.scalers = data.scalers
 
 -- Settings from config.lua, persisted by Steamodded across sessions.
 -- Fallback defaults keep the engine usable outside the game (tests).
@@ -331,6 +332,24 @@ function JCA.is_rental(card)
     return not not (card.ability and card.ability.rental)
 end
 
+-- Sticker traps on a specific shop card, as caution strings. Per-instance,
+-- unlike JCA.cautions (which warns about the joker itself): the same joker is
+-- a fine buy without the sticker. Perishable debuffs for good after
+-- G.GAME.perishable_rounds (card.lua:2652); rental charges rental_rate ($3)
+-- every round (card.lua:2647), which can eat a money joker's whole payout.
+function JCA.sticker_cautions(card)
+    local out = {}
+    local key = card.config and card.config.center and card.config.center.key
+    local a = card.ability or {}
+    if a.perishable and key and JCA.scalers[key] then
+        out[#out + 1] = 'perishable: gains die in 5 rounds'
+    end
+    if a.rental and key and JCA.db[key] and JCA.db[key].gives.money then
+        out[#out + 1] = 'rental: rent may eat its payout'
+    end
+    return out
+end
+
 function JCA.is_perished(card)
     local a = card.ability
     return not not (a and a.perishable and (a.perish_tally or 0) <= 0)
@@ -732,6 +751,11 @@ local function tooltip_rows(card)
     end
     local caution = in_buy_area(card) and JCA.cautions[key]
     if caution then text_row('Caution: ' .. caution, G.C.RED) end
+    if in_buy_area(card) then
+        for _, warn in ipairs(JCA.sticker_cautions(card)) do
+            text_row('Caution: ' .. warn, G.C.RED)
+        end
+    end
 
     -- Copiers in the shop: a purchase always lands rightmost (see
     -- copy_source_if_bought), so say what THIS board hands the copier the
diff --git a/synergies.lua b/synergies.lua
index 85e126f..83b80e8 100644
--- a/synergies.lua
+++ b/synergies.lua
@@ -354,6 +354,21 @@ local CAUTIONS = {
     j_gros_michel = '1 in 6 to self-destruct each round',
 }
 
+-- Jokers whose stored ability values grow across rounds (Ride the Bus's Mult,
+-- Hologram's xMult...). A PERISHABLE copy of one of these is a trap the card
+-- text hides: perishable debuffs the joker for good after 5 rounds
+-- (Card:calculate_perishable, card.lua:2652 -> set_debuff), so every round
+-- spent growing it is investment about to be wiped. Computed jokers (Bull
+-- reads your money, Abstract counts jokers) are excluded -- they lose nothing
+-- stored -- as are round-scoped ones (Hit the Road resets each round) and
+-- Egg, whose sell value survives a debuff.
+local SCALERS = {
+    'j_ride_the_bus', 'j_green_joker', 'j_obelisk', 'j_hologram',
+    'j_constellation', 'j_campfire', 'j_vampire', 'j_lucky_cat', 'j_caino',
+    'j_yorick', 'j_glass', 'j_flash', 'j_red_card', 'j_madness', 'j_trousers',
+    'j_wee', 'j_square', 'j_runner', 'j_ceremonial', 'j_castle',
+}
+
 -- How to phrase a tag link in the tooltip, from the partner's perspective:
 -- `give` when the partner provides the tag, `want` when the partner consumes
 -- it, `both` for cluster tags where the pair simply shares the theme.
@@ -471,5 +486,9 @@ for _, entry in pairs(J) do
     entry.gives, entry.wants = g, w
 end
 
+local SCALER_SET = {}
+for _, k in ipairs(SCALERS) do SCALER_SET[k] = true end
+
 return { jokers = J, pairs = PAIRS, clashes = CLASHES, cautions = CAUTIONS,
+    scalers = SCALER_SET,
     tag_text = TAG_TEXT, tag_order = TAG_ORDER, theme_info = THEME_INFO }
diff --git a/test.lua b/test.lua
index 7756828..89c711d 100644
--- a/test.lua
+++ b/test.lua
@@ -658,6 +658,32 @@ eq(JCA.consumable_partners(consumable('Booster', 'Buffoon')), nil,
 eq(JCA.consumable_partners({config = {center = {set = 'Voucher'}}}), nil,
     'a Voucher yields no consumable advice')
 
+--------------------------------------------------------------------------------
+section('Engine: sticker cautions are per-instance, not per-joker')
+--------------------------------------------------------------------------------
+
+-- Every scaler is a real joker; a typo here would silently disarm the caution.
+for k in pairs(JCA.scalers) do
+    ok(JCA.db[k] ~= nil, 'scaler ' .. k .. ' exists in the database')
+end
+
+local function stickered(key, ability)
+    return {config = {center = {key = key}}, ability = ability}
+end
+
+eq(#JCA.sticker_cautions(stickered('j_ride_the_bus', {perishable = true})), 1,
+    'a perishable scaler earns a caution')
+eq(#JCA.sticker_cautions(stickered('j_golden', {perishable = true})), 0,
+    'a perishable static joker loses nothing stored - no caution')
+eq(#JCA.sticker_cautions(stickered('j_golden', {rental = true})), 1,
+    'a rental money joker earns a caution (rent can eat the payout)')
+eq(#JCA.sticker_cautions(stickered('j_baron', {rental = true})), 0,
+    'a rental non-money joker is just a cheap joker - no caution')
+eq(#JCA.sticker_cautions(stickered('j_ride_the_bus', {})), 0,
+    'no sticker, no caution')
+eq(#JCA.sticker_cautions(stickered('j_mod_unknown', {perishable = true, rental = true})), 0,
+    'unknown keys never warn and never error')
+
 --------------------------------------------------------------------------------
 section('Data: themes are reachable')
 --------------------------------------------------------------------------------