I've tried so hard to make work, and ended up with this version with so many small synergies.
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At first glance, this deck looks weird, and if you really want to you can play it by using dolphins and sirens as damage, and antimatter as creature control. During Additional Arsenal, I played it like that cause this deck is still quite slow, fragile, and not hard to disrupt with everything being quite expensive.
The big thing this deck is centered around is Antimattering Dolphins AFTER they get the triple'd attack from diving. Dives give an additive buff that the game remembers, and will subtract that bonus attack after a single action. So a 7 attack dolphin will burrow, and come up with 21 attack (plus 14). If you antimatter at this very moment, it will have -21 attack, and then after it acts, it has to subtract that 14 attack, meaning the dolphin will have a base of -21 + -14 = -35 attack. Now you have a very high negative dolphin, that you can burrow, and come back up with -105 attack, and the deck has a bunch of Antimatters... you can figure that part out :^)
This combo is expensive, and you won't always be able to play them back to back, and that's where the dark mark comes into play. Cloak is cloak, and if you play the pieces every single turn, 1 undisturbed cloak is just enough to do the full A. Dolph combo without your opponent seeing any of it.
Siren really helps glue this deck together. If things go awry, its great extra damage to use opponent creatures for damage, but it also helps stall when you have a negative attack dolphin. Healing 21 hp, 35 hp, or if you dive your -35 attack dolphin, you can heal 105 hp with a single siren sing. These 2 cards are worth making this water/entropy combo a trio, as the amount of dark needed is not very much. Often 4~6 dark is all that is needed in a game, and you can metamorphosis into Entropy for the rest of the game.
The only thing this deck has going for it when it comes to farming is that an Antimattered dolphin is a priority for the AI to keep alive in every way possible. It will do everything in it's power to give it more hp like through magma, and avoid doing any damage or killing of it. And when using Antimatter on your dolphins, it is meant to finish the opponent that turn after diving. It can't do that vs AI with increased hp, so a 35, 105, or 175 attack dolphin is the juiciest target possible for an AI to focus on.
- Side note, this same technique also works with Wyrm and Pegasus, but it takes more Antimatters to ramp up the attack since those creatures only double from dive, while dolphin has a much higher base attack and triples in strength. Mathematically, Antimattering at the peak of a dive will triple the base attack of Wyrm/Pegusus each time, and quintuple (5x) the base strength of dolphins, and you will feel that difference if you ever try it. Also, if there were no cap to creature stats, if you use all 6 antimatters on a single dolphin with no other buffs and maximizing the attack gain, you could get a dolphin with a base attack of 109,375, and a diving attack of 328,125 -