Far Cry 3 Blood Dragon

After the Main-Quest I got 19 Dragon kills.
I saw a spawn pattern for the Dragons post Story Missions and it works like this.

1.Fast Travel to the Outpost on X:521.7, Y:466,5
2.Then use the right entrance to leave the Outpost.
3.Go a few steps forward until the Way splits and throw some hearts to the left side.
4.Wait a few seconds and go left and there should spawn a Dragon.
5.Kill him
6.Press start to get in the Pause Menu
7.Save your game manually
8.Quit to main menu,
9.Continue your game,
10.Fast travel to the Outpost

Repeat

edit: Mr Maka91 was so friendly to make a video. Thank you very much

I found this place totally by accident after completing the main game and taking all the outposts.

Short and sweet guide:
1. Go to X:548.2, Y:473.4
2. You should be stood on a cliffside overlooking a river where there should be a blood dragon.
3. Kill it from a distance using the killstar.
4. Wait a moment for another to spawn in feel free to look around or move a bit if needed.
5. Repeat until achievement unlocks.

Apparently if there are scientists nearby then dragons may not spawn so make sure there are none nearby when you try this and you should be dandy!

You only need to wait a few moments for the next dragon to spawn just like in the video saving and loading is not required at all.

Video below showing me doing this when I realized what I had found and had to share it with you guys. Good luck!

So, they patched the game awhile ago so that you could reset garrisons. If you have completed the game, but have not killed 25 blood dragons. No worries, and no sitting around waiting for them to spawn.

Press Start -> Gameplay - > Reset Garrisons

Once the garrisons are reset and red and repopulatedwith omega soldiers, like at the beginning of the game. You get the killstar and can demolish anything that stands in your way, make sure to deactivate the shield which will spawn a blood dragon per garrison to kill.

No need for any saving, quiting, going back to main menu and stuff like that. With my solution you walk back and forth between two neighbouring garrisons and kill a dragon at a garrison everytime you arrive at one.

What I think is very important for this solution to work, is to not liberate any garrisons, except for the first one that comes with the story.

What also helps, is playing on easy difficulty and completing the story line because

So, on with the solution.

South of the first, and only, liberated garrison are two more. I have named those A and B. See this image: http://nl.tinypic.com/r/o5rwj9/8

Follow these steps:

1. Go to A and run past the guards (Try not to kill any of 'em because you don't want to liberate the garrison). Look for the bright green omega icon on your radar. That's where you can turn off the garrison's dragon shields. The one in garrison A is on top of a tower. You can climb the tower from within, using a ladder or you can jump to it from nearby structures.
As soon as you press the green button, the garrison shields will be turned off and a dragon will enter the base.

2. Kill the dragon.

3. Leave the garrison (still, don't liberate the garrison, just run away from it).

4. Run towards garrison B.

5. As soon as you arrive at garrison B, you will spot a dragon with a braincage just outside the right gate of garrison B.

6. Kill the dragon.

7. Run back to garrison A and go back to 1. of this list. Repeat until achievement pops.

In short:
*Don't liberate any garrisons, except for very first one from the story.
*Keep running between garrison A and B, turning off the shields and killing the dragon in A and killing the braincaged dragon at garrison B.

At first, when freeing garrisons, the weapon that does the most damage against the blood dragons is the C4, but you only carry a couple of them. However, when the game finally lets you to freely explore and no longer fails you for deviating from the given objective, you'll often find enemies on the roads. They will come in cars with a mounted weapon on top. If you can get them to leave the car or if you can kill them without destroying the car, and then hijack it, these mounted weapons as well as the turrets found in some of the garrisons make a lot of damage to the dragons. Use this method if you want to dispatch them quickly and without running out of ammo or spending extra money on extra ammo.

Remember that the dragons will show up each time you take a garrison's force field down.

AND ALSO:

You can spawn INFINITE dragons to kill on the very same spot IF you do the following:

- During the "Go to the Dam" objective, after the explosives that you planted fail to blow up, you are told to go meet a civilian engineer. Once you're on the bridge, instead of advancing through it, jump off on the left side of the river, then swim all the way onwards. Then once you reach the rocks beside the fence by the objective marker (where the civilian is) climb them to get where the dragon marker is. The dragon is going to be there pretty much alone and waiting the regular turn of events (at some point the game even tells you to throw a heart to attract the dragon to attack the enemies. Do not do that). You're going to kill it instead and then go back through the same way you came from, back to the beggining of the bridge (again, avoiding the objective marker). Once you get there, a new dragon will spawn back on that same place you just came from, so rinse and repeat.

That way you can farm dragons and get this achievement out of the way without worrying if you'd find enough dragons or if you would need to reset the garrisons after freeing them all (this way you won't have to). Another advantage of this method is that you will end up farming XP too (each dragon gives you a whopping 5000 experience) so you'll reach level 30 in no time. That's how I unlocked Hail to the King earlier on.

Finally, just as a reminder, there are quite a few elite enemies on the bridge, so remember to kill them with headshots, so it also counts towards that other achievement.

If this solution helps you in any way, give it a thumbs up. Cheers!