[When Digivolving] You may play 1 blue level 3 Digimon card or 1 level 4 or lower Digimon card with [Aqua] or [Sea Animal] in one of its traits from one of your blue Digimon's digivolution cards without paying the cost. Then, you may place 1 blue Digimon card from your hand under this Digimon as its bottom digivolution card.