Shepherd
Strength 2
Move 2
Hammers (same as worker and also able to be built with food)
Available with: Animal Husbandry
This unit would have a special ability called "Herd Cattle", herd pigs, sheep, etc etc and so on. When used on a tile containing that resource it consumes the resource, removing it from that tile, forever destroys its herd ability and gains a new ability (perhaps via promotion, the mechanic part is not my concern) that when used on another tile inside your cultural borders with no other resource to place on that tile a the resource, and its related improvement. However, should this tile ever be pillaged, both the improvement and the resource are destroyed (along with a great amount of gold provided for the pillager).
In addition, activating the "herd cattle" ability should be considered hostile, and thus an act of war. Further, I think it should earn the stealing party a permanent -1 per use with that civ. The "range" of hostility should also count not just inside cultural borders but within X tiles of a city, 2 (3 for kuriotates) +1-3 seems fair. I lean towards making it a flat 3 (5 for kuriotates) and not allowing a shepherd to move into a tile with any non invisible unit not of their own civ, allowing other players who are in the know to garrison their horses and sheep for later use.
Now, thoughts on implementation are uninformed at best. I don't know how or what a tile improvement can do. I imagine something not so unlike the tomb that provides life mana. A graphic that looks like the improved resource (corral on cattle) but is a single entity that can be pillaged.
Flavor wise, the unit finds an area ripe with a kind of livestock, and herds most of them together to move them elsewhere. Where as normally an animal resource such as this is indestructible (cattle or horses set free learn to live normally in the wild) these are artificially present under less than ideal conditions, so upon the destruction of their artificial habitat they go freely out into the wild and are summarily devoured or reduced in quality/quantity to the point of being useless on the scale requried to be a tile resource.
Balance wise, this rewards the malakim for early exploration, malakim players in their thirst for cattle and horses will have a much, much wider swath of the map explored on a given land based map far before other players. This constant exploration (and consumption) leads them to have better maps and contact with more civs earlier than most other players. This would make them "feel" nomadic without actually being nomadic. Sure, their big cities stay right where they are, but they have units and "unit bundles" (scout, defender, shepherd) ranging further afield than just about anyone else, these "unit bundles" might even be likened unto representing wandering tribes, especially later when upgraded to hunters with their precious shepherd payload.
In addition in mid game their role as wandering traders knowledgeable of the world abroad is further aided by their posessing most, or at least more, of certain resources than other civs, allowing them to combine their knowledge of locations and routes with their supply of animal products to trade far and wide, making their cities trade hubs, which has a feel I think is in line with the malakim overall theme.
on the surface this strategy seems very powerful, but that depends entirely upon the effects armageddon count 40 has on the acquired resource tiles. If they are destroyed, and unable to be rebuilt as per the pillage rules, then the malakim have a very practical reason for averting the end, or near end, of the world. This motivates malakim players further to do all in their power to slow, stall, or even stop the clock, which enriches their flavor as a civ further, cementing them into their role as averters of the apocalypse.
While I think that is a bit harsh, I will state my opinion on how it should work. Each tile that has its resource destroyed in such a manner should be enhanced in some way, perhaps a flat +1 hammer/food/gold bonus on the tile, or a percentage chance for each, I don't know, but just acing them entirely seems a bit draconian, even as a balance factor. Losing the resources but retaining some of the production bonuses seems a fair balance.
Graphically, hard to say. Hunter is an easy cop out, or scout, I believe scout might be more appropriate. For the tile I think a combination of a cottage and the raw resource (a little hit in the middle of a herd of sheep) might be nice, but I don't know how such things should layer.
As a final sidenote, if all the code is written for this ability, I would just LOVE To see Great Scientist units for the malakim to be able to "morph" into an herbalist able to do the same thing with plant resources. That's an entirely other can of worms though, but I'm just saying.