Time is of the essence in this map, so keep tabs on the Quest log. You also have to do several things simultaneously. You find yourself in a lovely shantiri scenery with your three heroes, who have to work as a team in order to complete the main quest. The teamwork involves Kibwe helping Reem in the underground, and then Imani must help them both get back to the surface. The main quest, however, is to assault the main Academy town within 4 weeks. To do that, first the trio must split up and create a distraction; two targets must be taken (once one is taken, the other must be taken within two days) in a coordinated effort. This walkthrough will deal with the three heroes separately and their complete missions, rather than going back and forth between them. In this map, troop preservation is very important, especially for Kibwe and Reem.
First things first. Troops. Can't do anything without that, so use Imani to capture the town just southeast of your starting position. After that, head east to pick up free creatures and go across the bridge to capture the Gold Mine, Sawmill and Ore Pit nearby. Be careful; there are patrols coming, and they have titans. After taking the mines, go north and find the Altar of Ylath. It allows Kibwe to break a seal. After this, I sent Imani back to town to pick up reinforcements, and then back east to take the Tribal Outpost fort. Once that is taken (and rebuilt), you can send reinforcements very quickly. Move south and plunder the Crystal Cavern. You need to plunder 5 mines in total to complete the side-quest, but it's not necessary. Do not move east and challenge the army guarding the bridge; it is unbeatable.
Keep moving Imani south. Fight the titans and touch the monolith there, watch the magic happen underground, where Reem is – she should now be able to board the ship there.
Reem starts out with a really nice artefact just north of her position, but before engaging the neutral guards, head south and pick up the free stack of creatures. Then move her south and capture the Gold Mine there. After clearing her area and moving across the bridge, Reem arrives at a garrison she can't attack. What to do? Well, just north of the garrison there is an underground passage. Head down and make your way quickly through the cavern, to find yourself on the other side of the garrison when coming back up. Go back towards the garrison to find free creatures, then head east to the two-way portal. Now you're back in the underground, with more free creatures and loot. You have to wait for Kibwe to visit the purple altar to go any further. When moving onwards, you arrive at a ship which becomes available when Imani touches the monolith above.
Get on board, head for the whirlpool and find yourself magically back on the surface. Head east and you find the town that you should be able to take if you have conserved your troops. Once Reem takes the town (Burtuqaali), her job is done. She can wander around and grab resources.
Kibwe, meanwhile, should capture the Ore Pit before taking the underground passage. After clearing the underground, he should take the northern stairway. Moving north, he finds free creatures and more potential fights, but you don't have to do them all. Remember: don't waste troops. Move on through the seal Imani has helped you with. Head into the two-way portal and find yourself back in the underground. Grab the free creatures to the south and visit the Altar of Malassa. When that is done, he can move through the seal and find the stairway leading back up top. When going up, it will be on the other side of the unbeatable garrison. He is right next to the House of Invention fort, but remember: don't attack that until you're ready to attack the southern town too. Instead, plunder the mines or something. When Reem is ready to attack her town down south, attack the fort with the innovative name, rebuild it and the distraction job is done.
Once all of the above moves have been made, the two armies guarding the white bridge will leave, with the intention of retaking the recently lost town and fort. Don't let Reem and Kibwe fight those armies; you will lose and then the map is also lost. Running away the way they came is a good option. Keeping the town or fort is not a priority.
Now, have Imani cross the white bridge and go straight for the jugular: attacking Yasir in the town of Al-Jabr. First you fight Asad again and kick him to the curb. Then go for the final target. Yasir is pretty powerful – a level 30 mage – but as he only has a token army, you should win. And that's the end of the Stronghold campaign.