You craft them, the engrams can be found at the end of your mod list :)

i see thank you! :)

@Kiety, may I make a suggestion for Death Worm horns? Currently, there are too few death worms on the server. If I knew how to edit the .ini file I would allow for some alphas to spawn. If the spawn thing is too great of an issue, could we add a 20 > 1 rhino horn to death worm horn converter in the bin? It's taking incredibly long to tame a few mantis.