I think you will need separate learn abilities for each level, because within the learn ability you set how many "skill points" or "charges" are required to level up an ability. I wouldn't do it with charges though, I'd do it with a veterancy behavior, which display-wise is the same thing.
Or you can take the easy way out and make each ability an upgrade that requires an increasing amount of vespene each level.
@MacSC2: Go
I think you will need separate learn abilities for each level, because within the learn ability you set how many "skill points" or "charges" are required to level up an ability. I wouldn't do it with charges though, I'd do it with a veterancy behavior, which display-wise is the same thing.
Or you can take the easy way out and make each ability an upgrade that requires an increasing amount of vespene each level.
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