When trying to render one of these dragons unconscious, use a longneck rifle and tranq darts. I tried using a bow with tranquilizer arrows and sunk over 150 into a level 100 dragon and it simply flew away. Funny thing is, she passed out like 20 minutes later and my friend tamed her.

Using an ascendant rifle with 600% attack power took about 30 darts on a level 100, the dragon had about 13k torpor.

The rex kibble seemed to be over twice as effective for taming, at 10x tame speed it took about 5 pieces, so at normal speed a level 100 would take about 50 kibble, or an insane amount of prime meat.

It seems like the dragon fire won't work if it is an admin spawned dragon, so I would recommend trying to find one if you care about the fire, if not spawn away! Also, don't forcetame. I don't know what it is about it, but my server did not like my attempts to forcetame them, every time my server crashed. It might just be a problem on my server, so try it and if the same happens you have to tame em the old fashioned way.