If Umbral truly is earth, ice and water then it would be useful against lightning, wind and earth respectively.

If Astral truly is fire, wind and lightning then it would be useful against ice, fire and water respectively.

This is why I find those attributes for astral and umbral to be quite strange. The elements overlap in such a way that one if it's strengths is also a weakness.

http://i6.photobucket.com/albums/y24...entalWheel.jpg

http://common.allakhazam.com/images/...18ca741a06.png