The smoke in the effect below is made using billboards, not geometry.
The shadows are faked in the shader.
For the ice breaking effect below, I was inspired by the ice breaking VFX in Gears 5. The ice is a 4x4 grid of a tillable mesh. The mesh is broken into different pieces and animated with vertex animation textures to scale down. I use a mask to decide that part of the mesh that should be animated and by how much. You can see the mask on the black square to the left in the video.
Below you can see my first showreel. This was my first time making VFX. I have improved a lot since then, but desided to keep it because it showcases some skills that my new reel does not show. The particle effects are made in Niagara.