As far as the three types; main, alt, specific I can grasp them well enough and that tool you gave me would help. Speaking of which, I see what you're talking about. Your Raven's Purge Fire Release technique is the one you're referring too right? I believe you taught me that some time back.
Going back through the description and your guide; When I create the mushroom the poison would begin to spread through the air like a toxin. This is where the danger of wind release comes in since these toxins can simply be blown away or blown back at me. On that note, one of the questions I possess is the user's tolerance for the toxins of their own technique; and this can very well expand into all future techniques since I'd assume it would be consistent. If we were to come within the range of the toxins where we could inhale them wouldn't we also be affected by the technique? If it were blown back or we fell into the infected area? If we had some sort of breathing aparatus that protects us from toxins (and this can expand to opponents too) would that protect us? Specifically I'm speaking of non custom weapon bio items like what I have on my Regent bio. I have a mask that filters my breathing from poisons and toxins. However, not sure if it would work against chakra inhibited toxins as well. So those are my first set of questions revolving around the poisons.
Second would be about the spores manifesting main release on the bodies of my opponent. In the previous incarnation of the technique we grow actual mushrooms that that spread toxins. In this version we grow tiny spores that travel through the air correct or are they miniscule enough to be missed by the naked eye? Next, how does the manifestation of Main release (according to your guide) result in Death? Also what do you mean by advanced decay? Is the fungus that grows resulting in some sort of chakra feeding or deterioration of the victim's body? I remember seeing something about that in the main release. I just wanted to be sure that's what you were talking about.
Finally in the description of the technique it says the mushrooms grow on the ground/body. Do you mean the body of the user or the body of the opponent as if meaning you can manifest the fungus directly onto the opponent's body? If the former, what would growing the mushrooms on our own body solve? Continuing along those lines, if there were to be a jutsu that grew fungus or mushroooms on the host body it wouldn't result in the same effects as would be for if they grew on the opponent's body right? Similar to how we can cover ourselves with Decay chakra but not be effected by it if it's a specific jutsu form that armors ourselves.
Yes, Raven's Purge is the one. That technique allows you to burn objects and produce a carbon based smoke clone that encases particular molecules and substances within that object. You can then manipulate the toxin-carrying smoke directly into someone's nostrils, mouth, etc. This solves the issue of having to eat these mushrooms in order to feel the poison.
Most of the toxins can't filter through skin, and require injection and inhalation only. You need to do the research yourself if you're unsure. But most of the mushrooms I describe require inhalation or ingestion. You are immune to chakra created mushrooms that you produced. This means anything you created won't affect you, but the RL version of the mushrooms, that you didn't create, or other user's mushrooms, will affect you. Consider it something like Mei's immunity to her own PH manipulation.
Masks work as well, as long as the toxin we're dealing with does not transfer through the skin. No need to be chakra-related, if an object stops you from breathing the toxins, you can't do much.
The spores are tiny, think of it like polen dust. There's a lot of them, so you do see a opaque cloud, but each individual spore is very small. Now, they grow into Main Release fungus. I don't know why you have so much trouble wrapping your head around it. Fungus are the lowest trophic level, they are decomposers, they are the vector of the decay process, and that is what this element is about, way before Decay was a think ( which is more about destruction at a molecular level, rather than the biological process ).
This:
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Parasitism, Spread, Metabolysis. This is what Main Release fungus does to Biological and Mineral Matter, it turns everything to mush, soil and dust. So when a spore falls on your opponent's skin, he becomes those peaches, while also having his chakra drain (non quantifiable yet, unfortunately ).
With this jutsu, you can create mushrooms from the ground or from your own body, not from your opponent's body. You can, though, grow this mushrooms on biological surfaces like trees, plants, dead animals, etc. Just no living animals and that includes other people. Preferably you'd want to create them on the ground/plants, but if you are flying on top of a bird, several meters in the air, and so is your opponent, it's much more efficient to grow the mushrooms on your body if you want to affect your opponent quickly.