If you fulfil either path to the fullest, you gain a degree of mastery in the other - the mystic will develop magickal “siddhis” which the average aspiring magician would love to have, but on the path of renouncing all attachments, karmic entanglements etc., they’ll be useless distractions, and best avoided.
The magician will acquire mystical wisdom and come to realise he’s One with all things, that there is essentially No Thing and so on - but then he realises this places him accountable for everything in his universe, so he can’t really hide in it by fleeing the material world.
I’ve seen the most harm done to those who thought they could go a little along the mystical path of renouncing attachment, and then found that the manifest world renounced them back harder; I’ve seen people’s marriages break down, jobs lost, even children shunning their parents, so it seems to me that this is the more dangerous route to dabble with - trying a little renunciation.
No-one ever illustrates that since it has this moral aura of mystical wisdom, but I know so many people who got their lives ripped raw from trying a little of this stuff that’s really only suitable for those who want to be truly non-attached and live as hermits, or monks and nuns with other seekers.
The main problem is that the answer from gurus and spirits when this begins, when the crying bleeding student asks for help with a life that’s falling apart, is “This is a lesson” - the lesson being non-attachment is the only way to end pain, and the guru/spirit is correctly answering in alignment with the stated will of the student, and their belief system - but the student usually thinks, if they bear this long enough, eventually life will return to normal, but of course it can’t so long as the student is busy sending big “Fuck off, I renounce thee” messages to the manifest universe…
The point about merger and dissolution isn’t that you get to a paradise where all needs are catered for and all desires met harmoniously - it’s that you cease to desire, cease to feel pain or pleasure, and IMO this is mis-taught by a lot of western people, though it’s certainly well understood by Hindus, who advocate that for most people, they shouldn’t attempt this path because it escalates real fast.
The mystical truth of reality is that there is No Thing: that ego, desire and so on are illusions that often cause pain when they’re not fulfilled - but to live this truth even slightly will begin to cause the manifest universe and all things in it (relationships included) to begin to shun you like magnetically-repelled iron filings, because you begin to manifest the reality of total non-attachment and that repels anything you would normally have attracted into your life, except for more of the same “lessons” that cause MORE pain, and therefore make the person renounce even faster. It’s a simple and self-supporting system, and it works.
The magickal truth of reality, on the other hand, is all the above, with “So what?” added on - because the magician may have encountered the reality-illusion, may have dissolved his or her self into the great singularity, but they still want that Ferrari, a cheeseburger, and probably a nice pair of boots as well!
It’s somewhat the same as having knowledge about the shape of the earth - intellectually we may know it’s round, but we don’t normally need to act on that knowledge to lay a perfect floor or build a level wall, in fact we do better to cleave to the illusion of the ground being flat for both of those - and even when we do need to bear the globe in mind, it’s usually only so we can get somewhere for our own purposes, the simple knowledge in itself is basically useless in the majority of spatial decisions we make, and then only used as a calculating tool for larger-scale actions like (for example) flying to Japan from the UK, where we have the choice to go west or eat to get there.