Board Thread:Questions and Answers/@comment-26533134-20151013074106/@comment-24035373-20151015171842

leveling up an ability is not like leveling a unit's level. it does not build up like experience points, it's more like a lottery. using 5 scroll I in one enhancement definitely gives a level up. using a scroll I 5 different times does not guarantee a level, but if you're really lucky, you could get up to 5 levels.