I experimented quite a bit with special effects - you'll have to experiment with the custom effects if you really want control over what you're doing, and by experiment, I mean mess with every setting over and over until you get close to what you want. One thing to keep in mind is the "angle: -1" that allows you to specify the angle when the effect is generated. For example, this is what a 30' cone of flame looks like when it's a custom effect: { "angle": -1, "angleRandom": 30, "duration": 15, "emissionRate": 50, "endColour": [0, 0, 0, 0], "endColourRandom": [0, 0, 0, 0], "gravity": {"x":0.01, "y":0.01}, "lifeSpan": 20, "lifeSpanRandom": 3, "maxParticles": 1000, "size": 25, "sizeRandom": 15, "speed": 12, "speedRandom": 1.5, "startColour": [150, 90, 50, 1], "startColourRandom": [30, 20, 0, 0] } The angleRandom is the property that kind of sets the constraints on the particles, keeping them in a 60 degree cone (30 to either side of the basic angle), but otherwise they randomize within that cone. The "length" of the cone you need to set by looking at a combination of lifespan and speed. The example above is about a 30' cone roughly and can be set to start from the player. The same sixty-degree cone for a short range acid-spray, as an example, might look like this: { "angle": -1, "angleRandom": 30, "duration": 30, "emissionRate": 6, "endColour": [30, 20, 20, 0], "endColourRandom": [0, 10, 0, 0], "lifeSpan": 30, "lifeSpanRandom": 1, "maxParticles": 300, "size": 14, "sizeRandom": 3, "speed": 2, "startColour": [20, 60, 20, 1], "startColourRandom": [20, 60, 20, 0.5] } The lifespan of particles is longer, but the speed is much shorter - so it's a small cone that's fairly dense... Some older examples are here: <a href="https://wiki.roll20.net/FX_Library" rel="nofollow">https://wiki.roll20.net/FX_Library</a>