To tame a reaper king/queen, you need to attack a reaper queen(reaper kings will not work) until she’s is low hp. After that, she will sting you with her tail that will make you pregnant. After you wait a good amount of time, the baby will burst out of your chest. The only way to claim de baby, you need to eat reaper pheromones glands that drops from reapers. Good luck survivors!
It is the second strongest Reaper ingame. Only thing being better is the Alpha Surface Reaper. Getting impregnated by a queen lvl 150 and getting all 75 lvls possible for it gives you anreaper baby born with 15-20k HP which after imprint almost 30k. Dmg gets over 300% and after imprint close to 400%. Lvled can be 40k HP and over 600% if not 700% easily. Its a beast, can charge jump like a crab, take it down there to the drake nests and you can farm eggs for days. But be aware that light makes him weaker aka he takes more dmg and deals less.