Perhaps you could do it this way (no idea if it works, just a thought, e.g. with endurance aura and critical strike)
1. You give the hero both abilities (but you remove the icon of one of the abilities so it's not shown and can't be clicked, in our case lets say critical strike icon is removed)
2. You use a trigger that runs if the hero learns an ability, checks if the learned ability is endurance aura (the one having an icon) and if it's true, let the hero learn the critical strike ability (but I think there can be problems with the abilitiy-level)
3. Or you use 3 not-hero critical strike abilities (without icon) and, if the hero learns endurance aura, give the hero the critical strike ability concerning to the level of endurance aura