Originally made for my custom cube: BandaBox 3.

Theros had a polis way way in the past called Arixmethes. At some point, Heliod destroyed it (this may be what the FTV: Annihilation Wrath of God shows, or maybe Fated Retribution). On an unrelated note, Kiora was looking for big sea monsters, and the tritons told them about the biggest and most badass of Thassa's children. After most of Theros's storyline, she took the legendary boat of a legendary triton that's supposed to be of the few that knows how to get to the world's end through the sea. (She even fooled Elspeth and Ajani about her being said triton!) This led them to a hidden cave where they found the lost city Arixmethes! ...Except that thing wasn't really just a city. It was more like a city built on top of the biggest and most badass of Thassa's children. A battle ensued between Kiora and Thassa for the control of the creature, but we still don't know the conclusion.

I'll admit the idea of having a big monster that could be played in either ramp or a graveyard-centered deck was an environment concern, but I never lost track of making this worthy of being the definite sea monster of Theros. I actually think of the graveyard part as the sort of deep digging and exploration that Kiora had to do to find it. At some point, it cared about your library's size (again, it felt like digging for it), but it was trickier to cost that and make it attractive. The fight thing was my attempt to make it stand out (and make it more green) even as it just came out, and the wording was stolen from Polukranos, World Eater. I tried it being unblockable, having islandwalk, or being able to be blocked just by blue creatures, in an effort to give it a swimming feel (and justifying the blue cost, too), but it was too big of a swing. A super expensive creature that worked with your graveyard and annihilated your opponent's board was one thing, but the variance between then just killing your opponent or being chump blocked mattered quite a lot. The word count is also insane, considering I wanted an anti-reanimation clause and maybe a line of flavor text. And I was afraid that anything other than a simple evasion ability would just make the card lose focus.

Still, I wished it felt just a little more blue.

Can't you reword the second ability to fight any number of creatures?

No. Fight is only defined as involving exactly two creatures. Otherwise, Polukranos was going to have that ability. I do think it would be more aesthetic if it dealt damage equal to its power, not just a fixed number that happened to be equal to its printed power. It's a subtle difference, but all I see right now is a direct damage ETB effect, not a pseudo-fight. Plus that way you can "abuse" it with stuff like graft.