Mage Question

[Taelas]

There is always a 1% chance to miss no matter what level of the mob you are fighting.

For equal level mobs you need 4% hit (5% chance to miss normally)
For level + 1 mobs you need 5% hit (6% chance to miss normally)
For level + 2 mobs you need 6% hit (7% chance to miss normally)
For level +3 mobs (Bosses) you need 16% hit (17% chance to miss normally)

The only time you need spell penetration is when you are dealing with a mob that has innate resistance, but few mobs have any resistance, so spell penetration is usually worthless.

Those numbers are slightly off.

+0 levels: 96% to hit (+3% hit cap)
+1: 95% (+4% hit cap)
+2: 94% (+5% hit cap)
+3: 83% (+16% hit cap)
+4: 72% (+27% hit cap)
+5: 61% (+38% hit cap)
etc.

Of course you shouldn't ever have to worry about levels+4 or +5 or above, but still.