Normal: The airship that is supplied to the player (it looks like, but does not attack like, a Spitfire) is quite capable, so use it when the numerous enemy anti-air buildings do not prohibit that. As with all units that can be created at a distance, its dropped archers do not support a ground presence for the purposes of creating new units, although they can as usual operate switches and claim Power Wells. The airship can circle around the flying bird enemies and take no damage while still attacking, due to its turret attack. With Life Weaving and Unholy Power on it, it can defeat single Ravens on its own, even on Expert level.
Building up forces before teleporting may well be worth the wait, as the player is teleporting blind into the center of large enemy forces.
The far end of the island that is the destination of the first teleport has a number of enemy Mine-like traps. Walking a unit (need not be Swift) around the area without stopping is sufficient to trigger these without taking damage.
There is comparatively very little resistance at the destination of the third and final teleport, mostly because of being at 4th Era.
There are more than four orbs available on this map, allowing for variations from ordinary strategies without destroying and rebuilding orbs
XL creatures are tall enough to be able to attack the Ravens, even if they have a melee attack.
Once the scene with Mo begins on the final island, the player need only kill the wave of Ravens that appears; there is no need to panic as they almost inevitably kill Orbs and Power Wells on their way to the final island.
Expert and Advanced: For the first battleship that comes from the south (on expert) just dodge it and let it go to the main encampment. Once you are T3 on the second island start using Enlightenment + Mind Control to take over the Raven Battleships to make the map a lot easier. Then you can use the battleships to clear out the other islands. Regrowth + two Raven Battleships (maybe one?) will clear the main island with Mo on it, but you should have a LOT of T4 anti air for defending the final wave. I would make sure you have about six Raven Battleships for the final battle with the ship invasion. Keep an eye on your monuments as well. Two Giant Wyrms per orb should defend them well.
An Ice Shield on the Lost Disruptor added with the Shield Building spell protects it sufficiently for it to take down single Ravens, solo, on Expert level. The timing of the Ice Shield's replenishment works well with the Raven's slow attacks, where faster-attacking units might be able to inflict damage while the Ice Shield was down.
The Shatter Ice-like ability on the Stone Warrior will make much shorter work of the Ravens; it does full damage to single targets, despite what the text says, and can target these air units despite the Warrior itself being purely melee.