They are a jammer and they respond to their targets. This means they change frequencies often. Typically the are jamming staitons like Sound of Hope Chinese service. If you find a listing for that station you can predict when you have a good chance of hearing Firedrake.
Also remember that many times Firedrake does not come on until 5 to 25 minutes after the hour, so your best bet to hear them is from 30 minutes after the hour until the top of the next hour, when most Firedrake outlets go off air. Some Firedrake outlets do stay on through the top of the hour and do not break, but that is a minority of them.
Example, right this minute (1450z) Firedrake is up 15870, 15800, 14750, and 13130 kHz (and probably many more freqs, those are just what I saw quickly), but they will be off air in a few minutes.
T!
(edit)
1450z (probably until 1500z) 15870, 15800, 14750, and 13130 kHz.
1540z (probably until 1600z) I only see it on 2 freqs, 11970 and 9955 kHz.
2350z (probably until 0000z) I see it on 18180, 17170, 16920, 15800, 15550, 14980, 13920, and 13850 kHz.
2335z (probably until 0000z) Different day from above listing. 17300, 16920, 16100, 15970, 15800, 14700, 14400, 13970, 13130, and 12670 kHz
0025z (probably until 0100z) I see it on 18250, 17645, 17300, 17250, 17170, 16920, 16100, 15385, 14750, 13850, 13530, and 11500 kHz.
0125z (probably until 0200z) I have it on 17730, 17300, 17250, 16920, 16600, 14980, 14800, 14750, 13920, and 13530 kHz.
0225z (probably until 0300z) I see it on 17730, 17370, 17250, 17170, 16920, 15800, 14750, and 13850 kHz.