I had real troubles with this too, so I posted a thread! Here is a wonderful thread that fully got me getting it
click here to see it!
EDIT: The first % on a license increases when you kill that certain monster. After the first % goes to 100%, you gain the second % (or damage %) up by 5%.
So...
Ratmen Killer Wand:
0% (Damage:
15%)
When the
0% gets to 100%, the
15% will raise to 20%. Get the first percent to 100%
again by killing that monster, the damage goes up by 5%
again!
Ratmen Killer Wand: 99% (Damage: 15%)...
Get the 99% one more % and... Ratmen Killer Wand: 0% (Damage 20%)