Can you mess up a mother plant?

If I top too much, cut too many leaves off? I mean, if you just chop down to 12" and cut off everything, will that kill it? I had some plants too tall and I cut short plus took clones from and both plants are now kinda brown on top and not growing any new stems. I got to get a good technique going or it is not even worth it for me to keep mothers.

i would say, get a new mom if u can, and just keep taking clippings when they show up and premote the growth in new nodes rather then it growing up and out. Keep a time schedual when to take clippings and how many, Use soil and give it enough of everything so it grows slow and mantainable, Less light, less nutes...

you can chop as much off of a plant as you want, as long as you leave enough leaves on to allow photosynthesis to continue. I mean, it's possible to re-veg a plant after harvesting it, but it takes like 2 months for the plant to start growing again. unless your plant aquired an infection from the open spots where you cut it, your plant is capable of continuing to grow, it just may take a long time.

So once I top and say it is 18" will there be another top form in the same place? If so, should I use the top over and over?

there should be another top that takes over, unless you stressed it out so bad that it's growth has been stunted. and yes, you can top the plant over and over. quick tip tho- the top of the plant doesn't necessarily root the best/fastest. you should use sideshoots too.