I love death magic. Mainly because I find battlefield uses for it in all stages of the game, even when skill in death is low.
Skill Level 1 Death Magic:
- Versus the Undead use Dust to Dust (Thaumaturgy 1)
- Versus low moral units (such as elephants] use Frighten (Thaumaturgy 1)
- Versus anything use Ghost Grip (Conjuration 5)
Skill Level 2 Death Magic:
- Versus Super Combatants and Tramplers use Disintegrate (Alteration 8)
- versus the undead you can use Control Dead (Thaumaturgy 5)
- Versus most other things spam raise Skeletons (Enchantment 3)
And don't get me going on the wonders of Death 3. Every level of death up till Death 4 brings you something new and wonderful.
Shadow Blast is a great spell but don't use low level casters. The spell scales in both damage and on area of effect, so it is meant to be used by high level death mages, which is actually rather easy with some death gems and research into Construction.
Possibly my favorite spell in the whole of Dominions is
Ghost Grip. It is easy to spam and can be deadly against anything when the fight is drawn out. Also, don't be shy about using it against the undead, it effects them too.
Good luck and die well.