Most of the discussion about Soul Sacrifice has been about spells that force players to sacrifice their body parts. You can gouge out your eye to create laser shooting eyes or explode with bones by casting Gungnir. Other spells aren’t nearly as painful!
In fact, you can create rock armor by "sacrificing" a stone. You can also create a golem or flame armor by transmuting lava.
If you really want enemies to burn Salamander is your spell. Cast this and flames ignite your body and engulf enemies. After the spell is finished, your wizard is left with severe burns.
Excalibur creates a deadly sword… from your organs and spinal cord. While you can rend enemies, the caster dies after invoking Excalibur since well you don’t have a spine.