I was curious how much karma it costs to gain 2 dice in a skill, and so I sat down and did the math.
In general, the ways to gain 2 dice for any skill are:
1. Increase linked Attribute
2. Increase Skill Rating
3. Increase Skill Group Rating (if applicable)
4. Add Specialization
5. Purchase and bond a Force 4 QI focus (Improved Ability) (Adepts only)
6. Purchase gear (if applicable)
These break down into the following mathematical formulas:
1. ((Current Rating +1) + (Current Rating +2)) x 5; minimum (2+3)x5=25, maximum (humans) (5+6)x5=55, maximum (troll) (8+9)x5=85
2. ((Current Rating +1) + (Current Rating +2)) x 2; minimum (2+3)x2=10, maximum (11+12)x2=46
3. ((Current Rating +1) + (Current Rating +2)) x 5; minimum (2+3)x5=25, maximum (11+12)x5=115
4. 7
5. 12,000¥ + 14 Karma
6. Variable
Comparisons:
Specializations are the most karma efficient way of getting 2 bonus dice in almost every circumstance, barring cheap non-permanent situational boosts like Vision Enhancements (1,000¥) and similar. Raising a single skill from 1 to 3 costs (2+3)x2=10 karma, or 3 more than the specialization though the latter obviously doesn't always apply.
Maximizing an attribute is almost always preferable to increasing skill groups as the costs are identical but increasing an attribute also affects linked calculations and in some cases skills in the double digits count.
For Adepts, a Force 4 Improved Ability Qi Focus requires a Rating 4 skill to use effectively because of the Current Rating x 1.5 enhancement cap, and at a cost of (12,000/2000 +
=14 Karma is preferable to raising the skill to 5 and 6 which costs 22 karma. The downside is obviously that foci can be disabled and make you more visible on the Astral, but as skill ratings improve the cost benefit of foci similarly become more attractive. Depending on rules for upgrading foci used, a Rating 2 focus may be preferable given it's low Karma equivalent cost of 7 compared to raising skills individually.
Considerations:
Jack of all Trades, Master of None; this quality costs a mere 2 karma and pays for itself with two skill increases. As it does not apply to skill groups, raise skills above 5 as part of groups if possible for maximum karma efficiency at the expense of training time. Note that even with this quality you're better off raising skills as part of groups after rating 3 as the cost of raising three individual discounted skills from 3 to 4 (((4x2)-1)x3)= 21 exceeds the cost of raising a non-discounted skill group (4*5)=20. So your point of diminishing returns begin at Rating 4, not 5, and becomes progressively worse, but you may be raising skills you don't need.
Catlike; provides a +2 dice pool bonus to Sneaking tests for only 7 karma.
Natural Athlete; provides a +2 dice pool bonus to both Gymnastics and Running for a mere 7 Karma.
So, did I make any mistakes? Miss any clever ways of boosting dice pools (preferably permanently)? If you have any thoughts, feel free to share them!
