Trying to hold to the pipe, your body keeps growing massively, your tentacles reaching the depths of the lake and coiling out of it with ease, the rest of you amasses tons and tons of toxic mutant flesh, and soon you reach 70ft tall, the cliff can't hold your weight anymore and starts collapsing.
You instinctively try to wrap your tentacles around the structure, but they're way too huge and meaty and they end up crushing the rock even more, soon, you fall along with the remains of the cliff wall into the lake, and with that, the pipe breaks, leaking out gallons of toxic sludge.
Upon impact, you fall on your engorged head and produce a brief tremor, you shake your head only to receive a bath of the toxic water, which overflows and spreads to the nearby soil.
The toxic sludge in your skin and leaking into your suction cups feels horrible, like they're burning deep, and you trash around your tentacles bringing down even more of the cliff, and some trees.
Some stumps on your side grow and expand and engorge grotesquely to become two new pairs of tentacles, including the smaller tentacles that branch off them, giving you 10 in total. You blink rapidly as the tissue between your lateral eyes rips and allows the growth of another pair of eyes on each side.
A deep pain is felt in the middle of your head, as it starts to grow sharp teeth, then, a bursting sensation is felt as it pushes out, a fleshy tube with teeth bursting out of it, nearly half the width of the rest of your body, and rising about 150 feet into the air. The snakey limb then snaps it's primitive jaws and licks it's teeth with a long slimey tongue, before opening it's maw like a snake and letting out a monstrous roar. You soon gain control of this new limb and realize it's totally eyeless, as it can only feel vibrations and smell by flickering it's tongue like a snake. This new limb looks like a fleshy, slimy eyeless eel with a far more menacing snout, which looks like a combination between the flexibility and sleekness of a snake, with the brute raw force and the sturdiness of a T-Rex; it's teeth are definitely alien, looking crooked and extending far, each one almost the size of a human. Complimenting this, your snout let's out another roar by itself, showing how it's row of teeth extend out like the jaws of a goblin shark.
Your skin then begins to harden, adapting to the extremely acidic nature of the water, growing sturdy, thick scales all over except for the spots under your body and tentacles which remain slimey. Some of these scales grow boney protrusions that become spikes, which run through your tentacles all the way to your eel head.
Trying to push the rest of your body out of the water, you get a hold of the ground with your strong tentacles, but can only move so far. Your body senses your desperation, and between your body and the neck of your new head, a bulky mass grows, looking like the body of a dinosaur, or even a crocodile, although way bigger. From this new growth, two stubs appear on each side which slowly develop into a pair of massive arms, which become wide and extremely muscular, they're long enough to reach halfway through your tentacles and your neck, from them, you grow huge, webbed, sharp, and sturdy claws that resemble scythes, and with them, you reach to the rocky soil out of the lake and push your whole body out with ease. Out of the water, you spread out and try to liften. Your beak under your tentacles grow into a monstrous circular jaw with thousands of teeth, and from them, long retractable tongues with huge suction cups emerge. Your eyes have been displaced, now, two pairs of side eyes are in the newly formed pectoral muscles that connect your arms to your body, another pair moved to your shoulder blades, and the last, huge one, is in the connection point between your pectorals and your tentacle body. Your new spine slowly and painfully cracks, giving you a wide and dense abdominal region, giving you a strong support for your arms and eel neck right where your octopus body ends.
Trying to stand up on your tentacles turns out to be easier this time, they've become insanely strong, as the mutations give you an enhanced cell system, allowing your tissue to be strong enough to let you use your body with ease, regenerate in seconds, and much more.
Trying to walk with your tentacles, you soon develop a walking motion instead of stumbling around with them, allowing you to get as far away from the water and it's toxic fumes as possible. You can't get away fast enough as the last change happens, you fall to the ground, causing an earthquake and landing on your huge claws that mow down entire patches of forest, you growl in pain from another growth spurt, and roar as two stumps with teeth claw their way out of your torso, which slowly creep up and widen til around 50 feet as they become a pair of new monstrous heads, which produce a chilling high roar when they finish growing.
Panting and resting along a small (for you) mountain, you look at your body in disbelief, there's no way turning back, you've become a MONSTER.
Each one of your tentacles is as long as two soccer fields, and as wide as 4 lane highways. Your new torso is insanely muscular, has scales like a crocodile, and lifts you up another 50 feet. From them, vicious eyes can see in 360 degrees, and a pair of huge, muscular arms long enough to reach halfway your tentacles throb with power, their massive hands, big enough to bury a town square, have 10 fingers each, grouped and sticked together in pairs of 2 that give them an alien look, with claws made of an unknown material, stronger than anything ever seen before, that pierce through everything like paper. On top of that, you have three horrible heads, with necks 200 feet long each, you control each one yourself, thanks to your impressive brain mass, aided by smaller brains in each one of them, which sometimes make them a bit reluctant to your control and act animalistic by themselves. From tentacle to snout, you are well over a thousand feet long. You're no regular monster. You're a kaiju. A daikaiju.
You shake your heads in disbelief, hold your massive hands into a fist, and try to scream "NO!" as loud as you can. All you manage to do is let out a massive roar with all your mouths, a chilling, high, enormous alien sound.