The idea behind this is that spells are able to be "charged" by holding down the cast button.
For every arbitrary unit of charge (say 1-100), attributes of the spell would increase. Charged spells will therefore be more potent, cost more magicka, and expose the caster for a longer period of time compared to uncharged spells.
Example 1:
Fireball destruction spell
+3 units of damage
+1 unit of speed
+5 magicka cost
In the above example, those 4 modifiers gets applied to the base spell for every unit of charging.
Example 2:
Fireball destruction spell #2
+1 unit of damage
+2 units of AoE
+0.5 units of speed
+8 magicka cost
This spell will obviously have different uses than the one above.
Example 3:
Self-heal restoration spell
+5 units of healing
+5 magicka cost
Simple healing spell. More time + more magicka = higher potency.
Spells would be balanced in such a way that charging them will be moderately more effective than spamming the cast button.
How long it takes to charge a spell will be determined by their respective skill.
Thoughts and comments?