There’s an excellent monogreen Nissa available as well, but why not use blue? Actually, I’d rather use a monocolored deck in this particular environment, but I do have a fondness for Simic. Maybe we’ll get back to the other options later on. There’s Rashmi, Eternities Crafter as well.
This particular color combination is also interesting, because green can fix mana so much better than the other colors. Nissa lends itself to ramping quite well, so we should take that route.
I like these, because some of them are also quite potent attackers as well. Not all of them actually fix mana, but three of them do, and one sort of does as the Naga Vitalist can be useful, when you need double mana for something.
Personally, I’m not very big on the new ramp enchantments, but there are some worthwhile Sorceries for this.
Next, we’ll need something to ramp into.
We have some tools for card advantage here, but let’s add a little bit more of that, as well as some selection to help with Nissa’s 0-ability.
I might be overdoing the draw elements of the deck here a smidge, but… sure. We don’t have much room for anything else. supposing this deck plays 24 lands, which sounds about right with all the ramp, we have two more spots. That would be the right place for a few answers. Since we have Thunderherd Migration in the deck, as well as Drover of the Mighty, it’s not a bad idea to add a few dinosaurs (which we have way too few off) to the deck.