Its all personal preference... some people enjoy cannabis on HEROIN while some do not. Same thing for other drugs, some will feel that it will dominate drugs like ECSTASY and others will not feel this way.
Given that I showed the actual spelling for these terms, you're able to go to the search tab at the top of the page then to 'advanced search' and play around with the settings (such as searching 'title only'). Having done so, you'll find lots and lots of opinions on these topics as they've been discussed many times over.
Please have a look at the posting standards and guidelines (in my signature) to better understand what does and does not belong in OD and after searching around, if you'd still like to start a new thread on a basic drug combination, please do so in the Basic Drug Discussion forum.
If you have any questions, feel free to private message me.