Think we could post when we work on some cool stuff and show the process behind it. It took me a while to fully understand and now I am a master of dynamic parameters!!
Basically the slash effect uses a texture that only has a Red and Green channel: the Green is used for the black areas and the red is used for the emissive which has a colour that can be changed via the Particle Color node. Those two channels are then attached to a noise texture that dictates the shape that the erosion takes using a lerp node. (I personally and not a master of the Lerp and Power nodes but just understand that when it is used it blends something from 0 - 1 and that's useful for making things disappear)
Inside the particle system, you add a Float by Curve so that the erosion takes place over the span of 0.2 seconds or something and the texture completely disappears during its animation. To make it seems like there's movement, the UVs of the circular plane are flattened and straightened so that if you say, moved a texture along the x axis, it would look like the texture is moving perfectly around that circle.
It's then as simple as adding a panner to the noise so that the texture not only erodes based on the dynamic parameter but also erodes in a certain direction, giving off the illusion that the entire thing is slightly moving as well. It's subtle, but I want to get better at this so we can have effects that show a much more drastic movement of the texture across the UV.