I think that certain should be integrating with other enemies, example being egg layers (tentacles,spiders and flies) should be able to integrate with other enemies that have a way to lay them or be placed inside the enemy and once either two criteria are done (either killing it with a stick or waiting 15 to 30 seconds) the egg or eggs will leave the body by either the enemy NPC either the same way like syahata or just while the enemy is walking and the egg falls out to the ground with or without the animation to get the deadline or something
I will think more the next few days after using "mystical plants"
Edit: also for those who are wondering integrate is a more polite old fashioned way of saying sex as well as saying to combine