Imps don't steal mana because the opponent's mana doesn't decrease. Instead, they accumulate it from nowhere. But Specters do steal... :)
Actually, Imps are specifically engaged in stealing, as they take mana points from already cast spells, i.e., from one spell to another... while Specters absorb, because they can't steal by definition - they don't use magic and don't transfer mana points to their hero owner :)
Increasing the cost of spells can hardly be considered a spell itself...
Of course, it's up to you, Amber, but it probably wouldn't hurt to mention their ability...
That's exactly what I mean... ;) I'm not talking about my assumptions, but about a fact that exists in the game. If at least one upgraded Imp is alive at the moment a spell is cast, the mana gain is equal to 20% of the cost of that spell cast by the opponent... The exact number of Imps remaining doesn't matter.
It's hard to argue with facts ;)
