Your dream shows a magician, who is crossing the borders (= wall) of your space to live (= living room) and then taking all your room to breath (=strangling you). This can be understood as symbols for your inner realms: someone or something magical is intruding into your mental, emotional and spiritual space and literally taking it from you.
For now I see two possible meanings: Either a part of you is very superstitious or anxious concerning magic in general. This can be due to former beliefs that magic is something really evil. I think you can answer to yourself easily whether this might be true or not (maybe you've been risen in a very religious family or something similar ...). In this case the magic you performed on that day triggered this part of you and it popped up to warn you, that the EVIL MAGIC is intruding your system.
Or, if you've never been highly afraid of magic, it is a clear warning about something you did at this day. Something you've read or did by following the exercises felt like a menacing intrusion into your inner realms.
When you do exercises with visions and instructions given by someone else, you're actually not following your own intuition and not wandering the paths which lie before you by nature, correlating with the magical or spiritual issues which are active within you right now. Instead you're doing something which is embedded in certain beliefs and experiences of a person, who is strange to you and who might live in a world completely different from yours.
So something this person experiences as good and healthy, might be not so good and healthy for you. Some people can drink a lot of alcohol before they're drunk, others need just a sip.
In the blog article Josephine stresses out, that you shouldn't leave the paths she prescribes for you, because 'to do so will potentially open you up to predatory beings'. She's talking a lot of parasites in her books. This might have been her experience, that spiritual predators are lingering around everywhere, just waiting for some visualizing idiot wandering about the spiritual realms, inviting them to jump on their back and devour them. And her warnings already might have induced some fear, personalized as the wizard, who showed up in your dream.
Well, there are good news: You can wander around the spiritual realms as you love to, leaving prescribed paths and going where your own magical intuition and instinct is leading you without a big chance to meet such predators. Yet, by following step by step the instructions of someone else, his or hers exercises migth
install traps (and predators and closed doors where never have been doors and so on) within the world they build up within you. Actually you're installing them on your own by just strongly believing in and exactly doing what they say.
I don't believe that Josephine ever intends to install traps within her pupils, she seems to be a nice and very caring person! But while reading her books I found many restricting and sometimes - in my eyes - spiritually damaging views on magic. This is just my very personal opinion of course, which derives from my own experiences in the past, which led to a very strong desire to be completely free to choose my own ways and to examine the views and exercises of others for things which I know would deeply hurt me, if I would follow them. And dreams like yours would be a severe warning to me, that something I've tried is not good for me. - But this is me and you might be completely different, right?
Then there's the exercise with inhaling smoke. This could've triggered your dream too. While doing the exercises people read somewhere in a book, they might not really connect to their deep feelings, while they do the exercise. They just follow the instructions, visualizing to inhale white smoke and exhale black or grey smoke, without feeling much more than curiousity or the mood of trying something new or even nothing particular. What did you experienced while doing this exercise?
It is always good to think and associate a bit before doing an exercise like this. Why is the smoke white when you inhale and black or gray when you exhale. It is even said in the text: the stale gray smoke. This suggests, that the white smoke is something good and refreshing, while your inner realms are somehow stale and gray and must be cleansed in a way. But hey, did you feel stale and gray and dirty inside, before you did this exercise? Your inner realm is
you and nobody knows whether
you need some kind of cleansing or not.
And besides that: do you like smoking? What do you associate with smoke? Is it something positive, something you really like? What I do to find out, is visualizing a kind of laboratory, a test room for magic or a magical holodeck, where things can be tested (and deleted if necessary) without applying them to myself. So if you imagine a magical cloud of white smoke - outside yourself, without inhaling it - what do you see, smell, taste, feel, hear? Is it something nice or do you feel uncomfortable? Would you like to inhale what you experience here?
And you could do the same with black or gray magical smoke. Is that, what you experience here, something which you believe is inside yourself and must be exhaled?
In the end I don't know why you had this dream, of course. It is a direct answer of your inner realms to what you did that day. What I tried to explain here in my post is, that it is always good to examine an exercise both by thinking about it rationally, analysing, searching and learning about the implications and world views withing it and by association and experimenting with small parts of it in a magical way, being in close contact with all your senses and emotions, to find out, how you represent and understand the things, which you do, deep inside and subconsciously (so they become more and more known and thus conscious to you).
So don't get me wrong here. I don't recommend to stop doing Quareia. I am just proposing to work with the material in a different way, not just following it step by step how Josephine wants you to, but experimenting with it, learning and understanding what it means to
you, what it makes with you, how it's changing you, establishing your intuition and instinct for what is right and wrong for you. I believe, this way you will learn a lot about your own magic, and the course or whichever other magic you'll try will be the most rewarding for you!