Correct me if I'm wrong, but what karmic dice does is prevent 'failure streaks', right? When you have consecutive low rolls, it increases the chance that you will have a high roll. It is considered "fair" because it applies to both your rolls and the enemy's rolls.
It prevents streaks of any kind.
However, it has several huge issues:
1. By all the research done so far, it tracks success/fail, not high/low result. That means there is no difference between AC15 and AC20, as a few misses against AC20 result in the rolls getting "helped" into hitting AC20. If the enemy has an AC of 12, and you hit too much, you'll start rolling a few 1s and 2s, to keep it straight.
2. It really does not work with Advantage/Disadvantage, because it is "heavier" than it; Karmic rolls with advantage/disadvantage have a very pronounced tendency to roll "in the same vicinity". This means that you'll get a lot of, say, 17&19 or 4&7, but not as many 3&15, for example.
3. Combining the two above points, it can be gamed easily by using summons: conjure woodland creatures, animate dead, elementals; those spells can give your side creatures that are easy to hit, and don't find it easy to hit. This does more than just "soak hits" and "chip away"; think of them as "priming" your dice.
