Sultai Wild Nacatl 1/1 Snake that gets +1/+1 if you control an island and +1/+1 if you control az swamp.

Well, uhm, yeah, but naya colors are the creature/aggro colors so a 1 mana 3/3 "makes sense" there. With these colors it would more sensible to me if island gave it hexproof and swamp deathtouch or something along those lines. Maybe with +0/+1 and +1/+0 buff also. Idk.

By that logic Wild Nacatl should be either Abzan (best small creatures) or Mardu (three most aggro/small creature focused colours). Green should be able to get a Wild Nacatl with any other two lands types, except possible Temur.

While black has slightly better creatures in general than red does, red is better at small creatures. So naya is better than abzan IMO in this case, but abzan would not be out of the question. Since this design is centered around having variance of lands makes sense (domain etc) + green should have the best creatures in general even if it is lacking in weenies (although that seems to be changing ever so slightly recently) - a 3/3 is pretty much going over the weenie range p/t wise anyway. And this is a green slot were are talking about.

So... this feels best as a card that requires to have a Plains. I would say the other requirement could be for a Mountain or Swamp, but Mountains seems better. (Kird Ape & Loam Lion). However, Island requirement doesn't feel right to me.

Black gets two mana 2/2 and 3/1's with upsides. And before Shadows Over Innistrad block, black got better one drops than red. Black is supposed to better than red with small creatures, to the same extent that red is better than blue.

The card is more of a top down flavour as swamps/blayous/esturies are blue-black-green, as are snakes/naga. I liked the idea of Mirroring Wild Nacatl but I will considering changing the costs/effects if I can think of a better design.