Usage:
-abilitylevel [increase/decrease] [ability id]

Increases or decreases the level of the ability for the selected unit(s). Take in mind that most unit abilities only have 1 level, meanwhile hero abilities have 3 levels.

Additionally, increasing an ability's level past the amount of levels will instead make it use the ability stats from the first level and might be prone to bugs.

Examples:
-abilitylevel increase AHhb
(Increases the level of Holy Light for the selected unit)

-abilitylevel decrease AHtb
(Decreases the level of Storm Bolt for the selected unit)