Seal of baatorian Ministry of Mortal Relations pins an envelope addressed "To the commanding diplomatic officer".
Whoever opens it finds the attached letter
Below given is a return address."To Merited Keepers of the Peace,
Virtuous Champions of Order,
Heart and Blood of Sigil's Law
 - the Harmonium,
{Sense Motive/Spot/Diplomacy DC30: Whoever wrote this certainly went an extra mile customary sugarcoating.}
along with words of Respect for your continuous demonstration of heartly effort towards achieving a Better Tomorrow, on this tragic anniversary we wish to pass our deepest condolences. For little consolation this may offer we more than anyone understand the anguish of perdition. May the humble tribute attached with this message symbolise our sympathies and support for your cause. {Sense Motive/Spot/Diplomacy DC30: The tribute is a nice gesture, but you get a feel there is something potentially upsetting between the lines being said delicately here. You don't think it's a mockery, but the thought of genuine understanding from senders like this may be just as troubling.}
The Ministry's firm belief is that the Harmonium's rise to might over recent centuries along with its undisputable dedication to righteousness are enough to prove them a force to be reckoned with, and a partner worthy of discussion. {Sense Motive/Spot/Diplomacy DC35: Sugarcoating again, this time gradually scaling down. Textbook technique for managing your and other party's position of power in negotation. }
Bearing that recognition in mind we are thus pleased to humbly invite the Harmonium's representatives to a diplomatic summit, to open a channel of dialogue between our parties, in location of your choice. {Sense Motive/Spot/Diplomacy DC40: One could learn a lot from the baatorian diplomacy: while allowing the other party such choice may seem foolish - for the capacity to abuse it - and hence weak, this in fact is another display of strength, subconsciously relaying either trust or fortitude to withstand potential attempted abuse}.
Signed: on behalf of the Sigil Coordinator,
Aesmenoth
The Nine Hells of Baator Ministry of Mortal Relations"
When the box is opened inside found are four large buckets of shimmering yellow flowers. {Lore DC25: These are pyrite daffodils. A type of flower that grows almost exclusively in Nemausus. You begin to put pieces together. The tragic anniversary the devillish letter refers to must be of the the infamous descent of the the formerly Arcadian layer Nemausus to Mechanus - by many and not without a reason thought to be the Harmonium's greatest failure, an ultimate monument to their guilt, where somewhere in the allegedly dubious practices in "prisoner reformation" camps, ideals of law tipped away from ideals of good a step too far - so far a whole layer of an outer plane slipped away from the dominion of good}
With them packed are also around 50 platinum cogs and a few handful of valuable gems, few warding amulets, three Holy Avenger* blades, and a pile of contracts allowing the holder to summon a devil from Lower Planes to serve them for 2 hours; these include one amnizu, two cornugons, four hamatulas, eight osyluths, sixteen erinyes and thirty two barbazus.