here i am!
Grim,
you could safely vape cannabis with a very tiny bit of dried organic peppermint or spearmint, i've done it and it gives a nice taste, but no specific medical benefits that i noticed. mint family plants tend to expectorate and cool, but don't quote me on that. i would not use the root, the commonly used part of mint is either the leaf or the flower, but perhaps you know something i don't.
I haven't vaped licorice root (as opposed to the leaf, flower, bark, etc.) but it is generally regarded as safe, so i feel it would be doable. probably lend a nice sweet quality to the smoke. I have seen it incorporated into some old herbal tobacco recipes.
some herbs are indeed potentiators, meaning they boost the power of whatever herb they are put with. mullein is one of these herbs and i have heard that you can vape it. it is supposed to be a better than average expectorant, so it may make you cough up some organs if you aren't careful with it.
i understand that it can make cannabis more effective, but i have no personal experience with it. in fact i have a lil jar of mullein sitting in with my vaping supplies right now, it's been there for a month and i haven't had the balls to try it. it smells sweet and is another ingredient in herbal tobacco.
no matter what you add i must advise caution, go slowly and take note of the effects as you go along. Herbs are powerful medicines and must be treated with respect.
chamomile, lavender or hops would probably be safe to vape too.
I often used vaporized cannabis in combo with chamomile, scullcap, kava kava, valerian root, cramp bark or hops either in extract form or pill form. the combo of (oral) kava and (vaped) cannabis is particularly nice and can help alleviate the nausea that sometimes comes with kava kava root and it's rank ass dirt flavor. sniffed lavender or marjoram essential oils on a tissue or cotton ball can add some sedative effects to your buzz too, whereas something like peppermint or black pepper could lend a speedy quality to it.
I have also had the idea of adding a cotton ball with a drop of safe essential oil on it to the stash container - not directly on the herb - for flavor and/or therapeutic benefits. haven't done this yet either. next bag maybe.
I'd love to hear if you have any successes. I've mentioned that vaping something like cannabis, coltsfoot or elecampane with the correct essential oils could be used as a treatment for a stubborn, deep seated respiratory infection or the seasonal bronchitis like my father in law gets. Still waiting for an opportunity to try it out. If DH keeps smoking, i may have my chance to try it out this winter