Most regenerative monsters possess a "core" of some kind which must be destroyed in order to kill them. I've noticed this trope at least a dozen times in Japanese media specifically. In fact it's so prevalent that there must be a reason WHY monsters are like this (besides having an Achilles' heel). So I began investigating the subject.
Turns out that when a monster is smashed to a pulp, a core is a good thing to have.
- It acts as a beacon and centre of aggregation for the scattered monster flesh.
- It serves as a power source for said flesh, which now must survive without organs until they are regenerated.
- That is usually where the monsters brain is kept.
With this knowledge, I designed my monsters accordingly: They are artificial lifeforms manufactured by inserting a spherical core into a sort of putty liquid (let's call it monster-sauce). The sauce aggregates and hardens around the core. Then signals from the core make the cells in the monster-sauce differentiate into the various parts of the monster. This is a functional fictional manufacturing process because each core is identical and can be "programmed" to create any monster. Meanwhile the monster-sauce is homogenous and easy to mass produce. Dead monsters liquefy and are recycled while injured monsters can be regenerated by dipping them in the monster sauce.
In combat, no matter how many times the monsters are pierced, slashed or crushed, they will always keep regenerating as long as the core remains intact. The smallest of monsters are only about as large as their core, thus a single attack is usually enough to kill them. The larger monsters are a different story. Their cores are more heavily defended: layers of hardened flesh conceal and protect the core.
When a monsters core is destroyed they will disintegrate, turning back into the monster-sauce. However, if their core survives the traumatic injury (no matter how severe) they will begin regenerating following these five steps:
- Aggregate towards the nearest core.
- Form a spherical cyst.
- Harden and differentiate.
- Return to original shape.
Foreign objects will only be removed while the monster is in liquid form. Afterward it is too late. Things like arrowheads will stay embedded in the monsters flesh until they begin regenerating again.
The core is a solid sphere about the size of a football with the consistency of quartz.
So I ask you, valiant monster hunters, what melee weapon would be ideal to slay such a monster? The technology level is pre-industrial.