Stats:
Djinn
Metal - 800
HP - 2600
Speed - 1.2
Build Time (Unassisted) - 1m, 24.2
Lighthouse (aka. Beacon)
HP - 1500
A somewhat confusing unit at first, the Djinn is a very expensive unit yet can also be EXTREMELY useful if you plan it right. What we have here, ladies and gentlemen, is a bonafide Teleporter. The Djinn is capable of teleporting units from one location to another, from any distance, for absolutely no resource cost aside from the cost to field the Djinn to begin with. Let's take a look at how this works...
To teleport units, the Djinn must first place a 'beacon' (the Lighthouse mentioned above) anywhere on the terrain, including underwater. After placing it's beacon a blue line will be drawn from the beacon to the Djinn indicating the teleport path; the circle around the beacon is the area units must enter to be teleported. After the Djinn has reached the position where you wish units to exit, 'deploy' it so it can receive units. Then take the units you want to teleport and right-click on the beacon; they will then be warped to the Djinn one at a time. Now on to rules of teleporting.
Note that teleporters are strictly 'Point A to Point B', meaning they are one-way; you can only teleport from the beacon to the Djinn, and if you want to go somewhere else you have to set another beacon and move the Djinn elsewhere. The time it takes to teleport a unit depends on it's metal cost; a Blastwing or Dirtbag will be warped almost instantly, whilst more costly units will take considerably longer. You can teleport any land or amphibious unit; you can even have a unit on the beach with a beacon underwater and still be able to teleport. Gunships can teleport as well, though fixed-wing planes cannot; they will simply fly around the beacon on a guard order. Two neat tricks regarding the beacon; one is that you can queue additional orders such as move/fight after you right-click the beacon and they will carry those orders out as soon as they finish teleporting; this also means you can set a factory rally point to the beacon and then to the desired destination for streamlined teleportation. The second is that you can cloak the generator and/or its beacon and neither will be revealed at any point during the teleportation process, though the unit will be visible for a split second upon completing teleportation.
Whilst the Djinn does offer you a handy way of circumventing the need to build large aerial/naval transporter fleets for your armies, it is still a massively expensive unit and highly vulnerable to attack. You must also choose your teleporting locations wisely; if the beacon were to be destroyed or the surrounding area to become unsafe, you would need to move all the way back to set another one, then back to the exit point (which could have been overrun by then). I suggest procuring an aerial transport for this unit so you can quickly set up effective teleportation routes. All in all this unit is very risky; you're paying 1800 metal for a faster way to deploy your armies or for an instant, massive backdoor attack on someones position, but this thing moves at the same rate as an unmodified Support Commander and is very easily destroyed if you're not careful.