That is true, but for most of my decks I try to stick to the one block/world that the cards come from. That's just how I like to build my decks for teaching and creative design purposes. Also power boosting won't be as much of an issue since my merfolk will give each other +1/+1 counters. I mostly like the
Dive Down because; 1) Blue tends to be a more strategically imposing color to an enemy, especially in a competitive setting. 2) With
enrage and cards like sweltering sun running around a higher toughness would be crucial for a creatures' survival. I will admit that
blossoming defense is a good card, I just think that it would have a better place in another deck that I would build when I get to building decks for Kaladesh. But I d appreciate your suggestion, it is a thoughtful idea that I believe will help later on.