Really great idea, but this is unusable. Without a creature generator, you need a 9 card combo to make this work: Lungfish + Flooding + 7 other creatures (otherwise Lungwish would be in the middle row). Even playing a deck centered on this combo (i.e. 2 Lungfishes, 14 other creatures, 2 Flooding, 2 tsunami and 10 pillars) you would need to draw on average half your deck to pull the combo out. All that for what? A 7 (or 9) attack creature without an useful ability, that is vulnerable to both CC and PC. Adding a creature generator would only make things worse, as you would need at least 3 elements (there isn't any creature generator amongst Water and Earth cards). Just compare this with Graboid, which has +1 cost and +1 attack (once evolved), only requires 2 elements, and does not depend on a specific combo to be effective.
In short, I suggest a massive buff to this card. Either give it another way to be un-delayed, or make Estivation passive, and give it a powerful active ability. Then adjust the cost and stats depending on the ability.
