What is this graphical effect called? I was watching this trailer:
https://www.youtube.com/watch?v=pWh5388AEHw
and at 1:22, the player used a magic trick that created a sphere that warped the projection of the scene.

Does anyone know what is this effect?
I don’t think there’s a formally established name for it, but it’s generally known as distortion, warping, or refraction. It works by taking an already rendered version of the current frame, sampling it with warped/stretched texture coordinates, and, usually, compositing the result back in with the rest of the scene. One of the first games I know of that used it was Half-Life 2, for an effect when the Strider enemies fired their cannon:

For an example of what this looks like in a modern game engine, check out Unreal’s documentation.