If you take buff card, you have to take creature, if you take anything that uses element other than your mark, you have to take something that will feed its cost. I'm going to unhealthy extreme here, but there are cards that require certain conditions to be met in order to be useful. This card is exactly the same. The only difference is that Flood is not as common as creatures or pillars, or in other words, its harder to meet conditions for this card.
Sure it limits your deckbuilding options, but its obvious that this card is a "combo" card with Flood. (Though even if you dont manage to setup a board for flood, you can use it as heavy hitting, expensive spark).