Spark generators is shown when i cast unstable bolt, though unstable bolt is not electrical but arcane damage. However, a bonus to damage is not added, it is only a card that shows up. Many times i am attacked by greyed enemies (tip says that if they are grey they cannot attack) but when there is a group of units it happens quite often. They are also greyed even though they have number of cards, which are hidden to me (and one or more of them is attack card).
Spark generator affects arcane damage as well - but for arcane it makes it harder for the enemy to block. Every minion gets 1 chance to play an attack - so only monster figures on the map that are greyed out won't be able to play attacks, doesn't matter how many cards it has on hand.
