What do you mean by "tags" in this? If you mean what Roll20 used the term "tags" for (an early version of a filing system), then no, the Tags features of roll20 don't do much. I don't even think they are exposed to the API, someone else might be able to correct me on this, I've never heard of anyone using the Tags in roll20 for anything productive. What do you mean by visualisation, or when you say present? I think you mean either letting the Players see the NPC token on the map, or you might mean Popping-Up the NPC's bio sheet from the Journals (which can show a Portrait image and some bio text)? Yes, there are several different ways and ideas for displaying 16 NPC tokens and making them visible at-once, or maybe even ways to help expose/reveal Journals (character bios with Portrait, or handouts). A lot of these ways are "workaround" techniques that depends on what fits your needs. If you can, describe more about exactly what you're trying to do, using Roll20 terminology as much as you can. You can hide NPC tokens on the GM Layer, then you can drag to multi-select them on the GM layer > Right Click > Send to Token Layer. They will all appear at once. You could put a black box (using Roll20 drawing tool) over a group of NPC tokens, and then delete the black box in 2 clicks, suddenly showing every NPC who was under the box. You could do the same idea except using Fog of War (roll20 feature). You could get Roll20 PRO subscription and use API Mod scripts to pop tokens from the GM Layer to the Token Layer in 1 click (try the Mod called tokenmod for this). Yet another idea is make a new map Page that already has the tokens revealed. Wait until the moment needed, and switch the Players that you want to see them, onto the Page that has them revealed. If you were talking about revealing NPC Journals (portrait, bio), that would be different, and the answer isn't as good. Unfortunately. You can still get Roll20 PRO and use tokenmod script to change a group of NPC journals into viewable by: "All Players", but the downside is they won't Pop Up for the players. The players would have to look under their Jounal tab to notice that new NPC has been revealed there, and then they would have to click each one that they want/choose to open and view. I don't know if the API has the ability to force Pop-up journals, I think no. So in this case you would still be stuck with clicking each NPC journal and clicking "Show To Players". Someone else may come along with knowledge of whether or how to get API Mods to do "Show To Players". I think it can't do that. And I cannot think of a faster way to do "Show To Players" on Journals. No, there is no multi-select in Roll20 for Journals, that would let you select multiple Journals and change them all to "Show To Players" at once, the only ways to change multiple in-one-swoop would be the API Mods and even then it won't force the Pop-up Show To Players, it would just grant them permission to open the Jounrals themself. As far as I know.
