Here’s a quick tutorial on how I created a underwater caustic effect.
1 - Add in a World position node
2- then a multiple node: give “A” a value of 1 and “B” a value of 64
3- Divide those two together: “A” = World position node “B” = Multiply node
4- Plug the divide node into a component mask and mask off the red and green channels
5- Add in a Panner node and plug the mask into the coordinate connection then add a Time node and plug that into the time connection
6- Now you’ll need to find and add “Motion_4wayChaos” it’s found under “Engine Content/Functions/Engine_MaterialFunctions03/ComplexMotion”
7- Once you add that in plug your Panner into the coordinates(V2) connection
8- Create a parameter and name it “Speed” set it to 1 and plug it into the “Speed” connection
9- Add in your texture sample then convert it to a Texture Object and plug it into the Texture connection
10- Multiply all this by a parameter to control the intensity of the effect and plug it into the Emissive channel
11- Change your Material domain from “Surface” to " Light Function"
12- Add a spotlight to your scene
13- Under it’s properties turn off cast shadows
14- Then scroll down to “Light Functions” and add in your Caustics material.
Add that’s it!
I hope someone found this useful.