Today, to say something is in "Timbuktu" is to mean that it is far from the beaten path. However, Timbuktu was once an integral part of a thriving trading empire. Over the centuries a vast repository of manuscripts and books accumulated. This article provides research fodder for the Keeper https://en.wikipedia.org/wiki/Timbuktu_Manuscripts For this scenario, we consider that Mali has sadly fallen prey to civil war and sectarian conflict.
https://en.wikipedia.org/wiki/Mali_War provides enough background to base a scenario on.
In this scenario, the town of Dire, south of Timbuktu is being held by Islamist rebels. That is nothing atypical or supernatural. It acquires a mythos element when the local Islamist group https://en.wikipedia.org/wiki/Ansar_Dine leader in Dire (the fictional Sheik Iyad al-Rahman) acquires some of the Timbuktu manuscript collection during their occupation of that city. As a Salafist he was more or less expected to destroy these books, but he had a scholarly bent and decided to review them first. Among the tranche of documents he found a version of the Kitab Al-Azif. The spells contained therein are for the Keeper to decide, but there should be several. This work had thus far gone undiscovered by the various efforts to preserve and record the library. Sheik Iyad began to employ the formulae found in this book, initially rationalizing (before his sanity eroded) that God had seen fit to place this wonderful tool in his hands for a reason. The effects began to show up on the battlefield when his group seemed to have uncanny knowledge of when and where Malian army forces were to be found. A government force sent to recapture the town of Dire vanished, except for a few dazed and insane survivors who staggered back saying their fellows had been "torn apart by invisible demons" on approach to the town. Events on this line happened with enough frequency that US Africa Command https://www.africom.mil/ got wind of it and word ultimately reached Delta Green (the Program iteration in this instance). DG in turn sends a team comprised of US Army Special Forces (Green Berets) https://www.army.mil/usasoc#org-resources and intelligence community (CIA, DIA, perhaps a language person) personnel to the Malian Army to ostensibly "advise and assist" in fighting the Ansar Dine Islamist group. The actual mission is to go to Dire, kill or capture Sheik Iyad and acquire whatever hypergeometrical resources he may be using.
The agents can draw upon the Malian Army as cannon fodder, but it is not the most reliable of military institutions on which to base a successful operation. They have access to geospatial intelligence and can call in drone strikes or air assets with prior arrangement. However, the goal of this operation is not merely to destroy everything and cover it up. The orders are to actually recover the materials if at all possible. No additional US ground forces are immediately available, but a quick reaction force (QRF) will be on standby as rescue should things go badly awry. The town is defended by a highly motivated decent sized force of jihadis (armed with kalashnikovs, RPG's, mortars, grenades, heavy machine guns on technicals) led by an insane mythos sorcerer. Africom has attached a conventional non-Delta Green US Army Foreign Area Officer https://en.wikipedia.org/wiki/Foreign_area_officer liaison to the agents. How the players address the problems posed by these mission parameters is up to them.
Credits
This was an entry to the 2020 Delta Green shotgun scenario contest, written by Jaron Bernstein