Cannot be knockout tamed. To get one, you must be impregnated by a Reaper Queen. How to do so is below.

First, find a Queen. Bring her health down to roughly 2 percent, then she will make a desperate tail swipe at you. This will impregnate you with a reaper baby. Make sure to kill her before she burrows away or you will miss the chance to get the Pheromone glands you need to imprint on the baby when it hatches. Any XP you gain while "pregnant" will level up the baby inside you instead of yourself. When it gets close to birthing, within a minute, consume a pheromone gland and imprint on it.

Boom, Reaper King! They eat meat while growing up.

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