Heavily obscured cloud

In 5th edition D&D some spells, e.g. Cloudkill, produce an area that is "heavily obscured". Nothing to do with light and darkness, there is just something else, like a fog, blocking sight. Somebody standing right next to the cloud can see that there is that fog, but can't see through it. I was wondering how to best create this effect in Roll20 with dynamic lighting. Any suggestions?

Hi Tobold, As far as I know there’s only a couple of options... 1) Draw a polygonal line on the lighting layer, but that is fairly ugly as its a black splurge which is fairly ugly 2) What I do is literally just drop a cloud on the map layer, usually a cloud with transparent edges that covers the area you want, sometimes pasting the same cloud on top of itself several times to get the right opacity, and applying a tint, e.g. I am running a desert campaign with sandy tinted clouds ;-) Si

Heavily obscured is equivalent to darkness and should block vision within and through it, so I would combine Brookesi's suggestions: drop a cloud/fog image on the map layer, and draw a polygon on the dynamic lighting layer with a diameter slightly smaller than the fog image. That way, players can see the edge of the fog cloud and can tell what it is that is blocking their vision.

Since you guys have Pro accounts, I actually just updated a previous api script of mine that you might find useful. Here's what I would use for Cloudkill. Click to play animated gif.  This example actually uses a combination of my Spawn script to create an instance of the default token for a multi-sided generic spell token (sized barely larger than actual size - 4.1 x 4.1 squares), then my updated dldark script to create a gridded circle on the DL layer with a slight (15 pixel) buffer region to allow the source effect to be seen by players outside of the effect.  For an effect like cloudkill that moves after casting, I would set the sendToMapLayer parameter to false in !dldark, so you can move it in later rounds. Then just call the dldark script again after moving the source token. Deleting the previous DL circle and grid is easy because they are all a single path object rather than discrete lines.  

That's very cool.