Hi, I have item "Rain of Chaos", if it is bought by dreadlord hero that has the infernal ability, it will replace it with rain of chaos, allowing him to call 2 infernals instead of 1, if it is bought by any other unit, or if the dreadlord does not have infernal ability, it will give him back his gold (does nothing). My problem is, if i use it, the dreadlord will get the rain of chaos, BUT he can learn the Inferno again. I don't want to be possible to learn the Inferno again.