What Does It Mean!!???

Okay, so:

-6 mastery = -15% damage to frozen targets
15% Extra Ice Lance Dmg on FoF
15% Extra Frostbolt Damage Always

Situations

1. FoF and BF up - Dmg reduced by 15%
2. FoF only - Dmg unchanged
3. Deeped - Ice Lance Damage reduced by 15%, otherwise unchanged
4. No FoF/DF - Fbolt damage increased by 15%

To be somewhat more thorough:

1. FoF/BF - Fbolt+FFB Burst - Slightly reduced
2. FoF - Fbolt+IL Burst - 7.5% increase
3. Deep 4 lances - 15% reduction
4. Deep ilx2,fb, il - 7.5% reduction

k bi