To obtain a reaper king you must first find a reaper queen which you must then lower their health to almost dead after you have done this you will have to tank its hits for a while whilst you wait for it to impregnate you once it does this it will bury back underground leaving you at severely low health, at this point you should return to your base where you should have reaper pheramone glands which are obtained by killing reapers however whilst you wait you can gain experience by killing things which will increase the level of your reaper king after it burst, after the 12 hour long wait from first being impregnated is over you should consume a pheramone gland which will alow you to imprint to the baby after it has burst out of you withought killing you, after you have imprinted on it you just raise it much like any other meat eater feeding it raw meat until it matures however if you would like to aquire multiples of these creature you will have to repeat the process ovee again.
Since i cant find this anywhere. Reapers take reduced damage naturally so its a good soaker. Dont bring light pets near theese because they take more damage and deal less damage.The reaper burns when light is near it. Nameless will attack it tho. Sorry for bad english.
When raising no need to get a lot of glands for baby. Just farm like 2500 meat before birth
Take off all your stuff from inventory
Put on one gland and keep the 2500 meat on you
After birth feed the baby reaper until glands run out
Eat 10 meat to lower your Health and let baby reaper kill you
It takes all the meat from your inventory after killing you
So it now has 2500 meat when it only supposed to hold 5
That should more than take it to juvenile where you no longer need glands
Up too make raising easy for others. Good luck guys.