In order to get a reaper king, you must find a queen, found in Halls of the Reaper Queen, then you must hit it
via Rock Drake or ballista turrets until it has a reddish pinkish glow, then walk up to it with good armor and a couple shields, it will then sniff you and grab you with it's tail, when it is done grabbing you, you will be severely injured, you have 5 hours to grind xp for the queen, kill other queens for pheremone glands, and when the time comes, on the last ten seconds, eat a pheromone gland and have a cryo on you in a pen, claim it, and cryo it, when deployed, it will act normal. Now you raise it, and bam, you have a reaper.
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.
If you put foundations under the reaper it can not burry. This way you can keep farming the same reaper for the best stats because every baby reaper, even if its from the same queen, will have different stats.
you can not reroll stats with the same reaper they will pop the same every time
you can not find colored reapers until one pops, the color of the reaper will repeat from the same reaper but you will not know it pops colors til one pops, queen will look normal.
you can transfer with babies in you
shotgun spinos or reapers on drakes back for extra 75lvls
blackbox self with cooked meat for baby to harvest you when popping in a closed room(this way it cant run anymore and will feed itself almost to full grown on x4 if not full)
to get pregnant build the oldskool larger trap its more efficient on gaining reaper aggro and animations run smoother) and preferably build outside of rads, rads will instakill your baby if you get even a glimpse of rad sickness