If you've seen How Dangerous Are Ploppers?, you know that only 9 out of 10 Chompers that eat a Plop become a Plopper. This question concerns what happens to the 10th Chomper.
You see, that 10th Chomper doesn't just become an armored Plop or a goopy Chomper or a blob with a toothy maw! No, that would be too easy! Instead, it becomes one of two deadly, bizarre monsters: a Spikagi or Whackagi. This question concerns one thing:
They only come up to a toddler's waist, but they are lethal. The body looks like a cone, with four spikes coming off it for arms and legs; a pair situated just above the bottom, where the legs really should be, and a pair just below the pointy tip. They have two beady eyes and a thin line for a mouth, which can open surprisingly wide-if a Spikagi encountered a sunbather, they could eat them whole, but they’d have a very hard time moving around after that!
Each of their "limbs" is a thick cone that tapers straight down from the middle to form a nice, crisp, razor-sharp edge (and straight down from the base to form a deadly point). (Yes, these cones are cones with edges, making them a hybrid of cone and prism.) Basically giant spikes as thick around as a man's thigh at the base, and as long as one of those conical birthday hats, and their body is just a slightly bigger version of these spikes. Spikagi can rotate these spikes 360 degrees, and they move either by spinning sideways (like a wheel spider) or by walking. You'd think they'd fall all the time either way, but no; Spikagi have impeccable balance and can walk across a tightrope without any problem whatsoever.
They have strength and speed equal to the average toddler, a bronze shell as strong as enamel and as tough and sharp as a steel razor, and if that wasn’t enough, they can spring six feet up and six feet away in a single bound. (Obviously, their legs are much stronger than a toddler's, but everything else is about equal.) If you tick one off, they can fire one of their needle-like limbs with the same speed and force as a crossbow.
No, this does not significantly weaken Spikagi, because they are like starfish and can A) seal off the wound immediately upon firing and B) grow the limb back. They do this within two weeks. If they fire all of their spikes, including the central spike, what's left is a core that looks sort of like a d20, upon which is the Spikagi's face. (It's sort of like a skull, held within the shell).
Spikagi can roll at speeds of 30 mph in core form (45 when they have their limbs) and can still jump six feet in a single bound. As a secondary defense, the core has a shell that's every bit as strong and sharp and that of their spikes, which makes their corners and edges downright lethal.
Now, everything above considering, I have to ask: How Dangerous Are Spikagi?
Specifications For Best Answer:
The best answer will analyze the lethality of a Spikagi (its ability to harm or kill medieval Europeans) and its CRD (Capacity to Resist Dying) to determine how dangerous it is. CRD is based off a monster's durability, and how hard it would be for medieval Europeans with medieval weaponry to kill or harm that monster.
The best answer will also take the Rarity of Plops and Chompers into account, which have populations akin to rats in the wild. Chompers often eat Plop, just because they are there, and as stated before, 9 out of 10 of those Chompers will become Ploppers while the lucky one left will has a 50/50 shot at becoming a Spikagi.
Finally, the best answer will address whether Spikagi actually need flayfire or whether it's just too much. I don't want to be ridiculous, but I'm certain Spikagi need some sort of ranged attack in order to be a credible threat. If I am wrong (if the ranged attack is just too much) the best answer should tell me so and explain why.