You solve that problem by having one table with all the weights for a 1d10, and a different table with all the weights for 2d6. You could call one table wundeeten and the other twodeesix. As a way out there alternative, you could roll a 1d10, then add narratively the effects. Roll20 was not built to create automated games, just facilitate player moderated gaming across the internet - the crux of your problem is you are wanting a degree of automation that will require a lot more effort on your part to get working within the limitations of the program. You could go a sort of half degree, and create a single macro that will query you for the damage that was done, and you type it in and the output of the query options matches your narrative. You can then set this up as a macro button, so when ever someone rolls a damage roll, you hit the button, select the damage result from the drop down, and the macro chats out the description. If you do wind up going the script route, it might be possible to create a very fancy script that will 'listen' for a damage roll, and announce the narrative of that roll via a query - but the base roll20 has no way to pass arguments to functions, or even functions for that matter - even this script idea is basically setting up a 'bot' element who is simply looking for a specific text dialogue in chat to trigger, as opposed to an actual function call.