Tingalf/Ars Magicana is the best source.
Kiya
found this useful titbit for you at a site
Level 1: Trailbombs do 20 damage per bomb. Death scorpion has level 100. Spidermine does 20 damage. Required Clvl: 5, Magic Cost: 5
Level 2: Trailbombs do 40 damage per bomb. Death scorpion has level 200. Spidermine does 40 damage. Required Clvl: 11, Magic Cost: 8
Level 3: Trailbombs do 60 damage per bomb. Death scorpion has level 300. Spidermine does 60 damage. Required Clvl: 17, Magic Cost: 11
Level 4: Trailbombs do 80 damage per bomb. Death scorpion has level 400. Spidermine does 80 damage. Required Clvl: 23, Magic Cost: 14
Level 5: Trailbombs do 100 damage per bomb. Death scorpion has level 500. Spidermine does 100 damage. Required Clvl: 29, Magic Cost: 17
