brekkana replied at 8-8-2013 09:39 PM
Ok. Not sure if my pic will post, but can you tell us how to go from 0 to anything?
You have 2 ways to upgrade this:
1. using Sacrifice Slime
2. using another Hero (duplicate or extra)
once you have either of the above mentioned, you'd be allowed to select which you want to "sacrifice" to get the skill up. e.g. for green slime you get +100 (on the +0) detail. Note that once you've sacrificed a slime or hero, it'll be consumed so choose wisely on which you want to upgrade and what you what to sacrifice.