You can only tame them with rock drake eggs. Get a ravaged with high enough health, drop all the eggs together and run around for a while with the Basilisk. It is not a guarantee that it w il eat an egg as it passes over it. But with more eggs the chances increase tremendously.
Seems like raising a rock drake 1st will help you tame these. 1st raise a drake. 2nd collect a bunch of rock drake eggs. 3rd find a basilisk and while riding the cloaked drake drop the eggs one by one and it will eat them.
Actually the Basilisk only eats Rock Drake fertilized eggs. The wiki says that it should also eat other fertilized eggs, but currently it ignore them. Probably it's a bug, for now feed it Rock Drake eggs
3 min 30 second feeding interval it seems. I have better taming effectiveness by keeping it aggroed while running it in circles. Lvl 20 only took 2 eggs. Lvl 85 took 4. Drop 1 egg. Aggro. Let it feed. Start stopwatch. When ready to feed it rears up n screams but does not spit