The Elder Scrolls III: Morrowind · Spellmaking constraint
On Target spell cost
On Target effects cost more than On Touch or On Self effects, and adding multiple target effects compounds the cost multiplier.
How it works
The guide states that On Target effects have a 1.5x cost modifier compared with On Touch and On Self. Adding another On Target effect applies an additional multiplier to the cost accumulated before it. Its example gives a 100-point Fire Damage touch spell as 50 Magicka and the target version as 75; adding another target effect raises the cost further. This is a guide-described custom spell rule.
Read the supporting references
Steam Community :: Guide :: The Arch-Mage's Handbook - A Practical Guide to Morrowind's Magic System
Check the edition and source version for patch-specific details. Guide methodology.