It's just for the sake of the story. In Ar15 Alliance also tells us that Omar probably got the inspiration to siberite decay from artifact 4.nadwrazliwosc_zebow píše:I don't really get why Arabians should use artifact to invent the tech they just have in their siberite lab
* Desert warrior / sheikh
I didn't know desert warriors can't change class or drive cars

To be honest I never really considered a sheikh's and a mastodont's power vs. conventional weaponry. I only had my mind on the story

* Ar12 (0dd1)
Such kind of "2-stage" mission would be interesting. I agree the mission will need balance between "research" and "test on unwilling test subject" for it not to resemble Am12, Am13 or Ar07 too much. Regarding the plot it's good but we still need the context, i.e. the remaining missions. Missions can seldom be planned individually.
Ok I've been doing some thinking. There has been a good deal of nice ideas in this thread so I've tried to pull out the best and stick them together.
Ar12
Abdul orders Heike to find a suitable spot for researching and field testing siberite decay. Scientists believe artifact 4 holds the key so she is to bring that with her. She camps in the desert north of American territory near some siberite deposits (in the hope that noone will go looking here). Ofc Am had the same idea with their siberite bomb research and their base is not that far away we later find out. Legion has been hired by the Russians to end Am research and seize their results. Stopping their research is ok but Legion must not get the results. There should be some sort of incentive for the player not to kill off Am right away so the player has to defend them against Legion. Furthermore the player should capture at least one Legion member (order from Gensher) for interrogation.
Ar13
In the intro for Ar12 it's told that Ar found another artifact (number 5) in the mountains and it was moved to New Samarkhand for futher study. Now New Samarkhand is under attack by the Russians (partially because of the artifacts, partially because of Ru via Legion now knows about siberite decay and want to eliminate Ar before they can use it on the motherlode (Ru know about the motherlode but not it's exact location)). Instead of returning to New Kaaba Heike's team must turn south and defend the retreating personnel. This is you map layout 0dd1 with the addition that you must defend retreating friendly units. Omar joins after some time with mastodont and tigers. Since some friendly units are only persued by few people I hope mastodonts and tigers can be put to some use. You also have to guard the prisoners from Ar12 and Legion will try to rescue them with a surprise attack.
During Ar12 scientists noticed that artifact 4 had geo-remote abilities, always "pointing" to some direction south (spoiler: the motherlode). They want this further investigated so you have to do some readings around the map (kinda like Ru13 but without a lab). This is how Ar learn about the motherlode.
At the end of or during the mission Alliance attack New Kaaba and kill Abdul. Everyone else there pulls back to a smaller base further into the mountains.
Ar14
The prisoners reveal that Farmer has joined with Kozlov and are developing the siberite bomb and it's almost done. Heike and Omar prefer to look into the motherlode but Gensher refuses. He and UPF do not want to see such a weapon in Farmer's hands. Since Ar can't do much with the support of UPF, Gensher and Heike sets out to stop Farmer while Omar prepares for going to the motherlode.
Farmer's fortress has several forward bases, mines, kamikaze monkeys, implosion vehicles and ambushes. The player can take over some of the minor bases but time is short. The map should be somewhat of a maze. A little like Am07.
Ar15
I'm still a little clueless about this one but in the beginning Heike should build the vehicles she need and pick her men. No enemy attacks. She and Omar will then eventually attack the motherlode with what they've got (no base buildup). This will make a short mission and I haven't got any good ideas how to prolong it. Perhas something like Heike needs to pick up something from an enemy base needed for the contamination to work (all other was lost with New Samakhand and New Kaaba).