2D Camera "Haze" POSTPROCESS" Effect

Hi Everyone,

I would like to know if someone could explain me what to do in terms of Material, to create a 2D underwater "Haze or refraction, Post process effect in my 2D Game.
My Post Process effect should be displayed on the camera when the player enter in water and stop when it exit.

So i’ll simply use a Trigger in the level to enable/disable the blend process on my camera.

I thought follow the 8bit tutorial made by Epic, who change the Blending mode of the Camera & create a Material using the post process node but it seem he have dissapear in the new UE version (i’um using 4.4 preview now)