Add "Watt" cards with different names from your Deck to your hand, except "Wattrain", up to the number of Thunder monsters you control with different names. During your Main Phase, except the turn this card was sent to the GY: You can banish this card from your GY; Special Summon as many "Watt" monsters as possible with different names from your hand. You can only use each effect of "Wattrain" once per turn.
