How to craft 55 lvl booster.
You will need:
1. ability box
2. 50 lvl Jet Pack (booster)
3. 100KK race currency.
You can get two types of ability boxes:
Blood booster box
---------> pain booster ability
Pain booster box
----------> blood booster ability
4. Combine ability and 50 lvl booster at Hero.
The number of upgrade slots can be various. Korean random =)
To increase the booster's grade you will need to do the same combining recipe.
Every grade gives 1%. 99 grade booster gives 49.5% of accuracy.
Blood booster was fixed. (If you still remember) And gives only 15% of vampire on maximal grade.
Pain booster was not fixed. So it gives fully 49.5% of accuracy at 99 grade.