Guitar Gurnards Duonigis

If this card is Special Summoned: You can banish cards from the top of your opponent's Deck equal to the number of WATER monsters you control. You can target 1 Level 4 or lower WATER monster you control; increase its Level by its original Level. You can banish this card from your GY; 1 WATER monster on the field gains 100 ATK for each currently banished monster, until the end of this turn. You can only use each effect of "Guitar Gurnards Duonigis" once per turn.