Normally, the growth of living things were something predetermined. Sure, one may see changes such as a bodybuilder gaining more muscle mass, but in essence, there was a set limit and potential value for all physical traits. This was the Limits of Genetics, the preplanned blueprints of the body. Changes in DNA were a gradual process that took generations after countless generations to produce any significant effect. Even with Magic and Mana Beasts, such a thing generally held true. There were possible "evolution" promoted by Mana, but in the end, it was mostly either unlocking hidden genes from the ancient past or unpredictable mutations.

A rearrangement of what one already contained.

However, what the formerly apple tree was attempting was something different on a fundamental level. An amateur and forceful fusion with another being. Plant grafting. An established technique proven by modern science, however, that was with carefully selected plants with genetic compatibility, and usually only for young buds. Otherwise, rejection would ensure the death of both. It was impossible for different species to have a successful transplant.

At least as far as humans were concerned. The giant multiton wooden spider rampaging through the forest couldn't care less about what humans or others considered possible or not. It had to do it, and so it did. This is why what was a formerly dull brown spider was now covered in bright red pokadots and had sickly yellow splotch all over its body. It had went and offered, ate, the horrendous funguses that used to torment it in its youth. However, rather than simply allow the parasitic to feed off it, it was attempting forceful assimilation.

The tree's body was attempting to reject the foreign entity, their different genetic makeup causing severe rejections from both their autoimmune system, and although the tree had no organ or breakdown, it was certainly feeling the harsh backlash of the suicidal idea. Its Mana was running wild inside its body causing its control over its movement to falter, bits of large and vines quickly yellowed, and its bark was softening at a rapid pace as if undergoing rot and necrosis.

All in all, it was quite a sorry sight, however it kept consuming more and more shrooms as the ones I had used before quickly died. They were no match for its sheer vitality and couldn't hold on long enough to form any meaningful connection besides poisoning it.

Soon, the strange injection of the shroom's mana made it lose sight of its surroundings, unable to properly receive the mana echos with the internal chaos. Its vision dimmed until it was left in total darkness, its roots had long turned into a foul-smelling pulp. The spider collapsed, and its weight shook the ground and created a large crack across its back.

It couldn't move, it felt pain for the first time in its life. Something that transcended nerves. A breakdown to the most basic of levels of its very being. It felt as if a fruit left forgotten in the summer sun, rotting away into nothingness. Every vine filled with molten lead, a putrid pus-like film-coated its surface and it couldn't breathe. Even its terrible condition was miles better than the red mushrooms because while the spider still somewhat kept its form, the unfortunate fungi on top of it had mostly turned into black tar.

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Any animal dumb enough to consider the weakened and crippled tree an easy meal soon quickly learned otherwise, even the hardiest of scavengers with iron stomaches didn't last more than a minute after coming into contact with the two. As soon as they inhaled, inadvertently the swallowing numerous spores in the surrounding, they went out like a light. It was both a method of reproduction and self-defense mechanism of the Crimson Dream Mushroom, often used as a potent sleeping agent in many kingdoms. Its spore inhibited the ability of hemoglobin to carry oxygen, thus suffocating the victim, all of which enter into a deep slumber which only being able to see red for some time because of the body's drastically increased blood flow afterward to compensate.

The best part was that the spores were airborne.

Which was exactly why the spider used all its strength to consume some more. In fact, lacking any proper fine motor control or vision, it ended up face planting closest to where it remembered the patch of shrooms were growing, shoving more dirt, rocks, grass, and broken twigs into its maw than shrooms.

This clearly wasn't working out well for it, but the shrooms were a vital part of its plan to safely take down the bird and save its little pyromaniac.

The shrooms weren't sentient like itself, so working together was impossible, ideally, it had to somehow help the changes happening. However, it had no idea how to do that, which was why it did the most stupid and bullheaded move it could.

Make an absolute metric shit-ton of health potion and help for the best.

Every time its body broke down, it would chug a bottle's worth. Every time the shrooms started dying, it would give it a health potion or ate more fungi. This mad cycle of destruction and rebirth occurred countless time. Day and night had no meaning here, it had no need for sleep nor rest, and so on and on it kept going. A broken branch? A minor inconvenience. Its leaves falling off? Perfect- It had been needing more nutrients since it could no longer move. Self cannibalize was nothing new these past few days.

It was forcing both of their bodies to the limit, either adapt or die. And so another preposterous outcome was created, in which one's genetic was made to radically yield to the circumstances and an evolution which should've taken centuries was reduced to simply a handful of days. If the pair in question were animals then surely their cells would've already given up and gain genetic defects such as cancer or burn up their live spans from their lack of telomeres.

By the end of the week, the tree more closely resembled a putrid rotten slime than anything else, its legs had fused together into a clump, not even the most desperate creature would consider it a meal, but rather a walking biohazard. Its hulking mass had drastically reduced and it was now no better than someone's potted plant.

However, it had survived. It had triumphant against the odds. The reborn plant now more resembled a blue vine with glowing crimson spots. Crawling out of the melting remains of its body, the young plant was only all the more determined, leaving a trail of bubbling ooze behind it as with renewing clarity it followed the trails of the bird. Thoughts of its friend filled its mind. If there was even a single red hair missing...

Well, let's just say that-

After such a trial it was absolutely starving, and it already knew whose blood it hungered for. It won't be long now. Just wait, bird, because retribution was coming.

A rustle of grass from its right catch its attention, the head of the vine snapped over so quickly that if there was any bones in it it would've surely snapped.

Well, it was quite famished, surely a snack or two wouldn't hurt before the main course?

That day, an entire patch of forest miles long was silenced. Nothing was left behind, not even a single fragment of bone, and only the sturdiest and ancient of the trees remained to stand witness to the massacre that had occurred.