We don’t have decent scans of Nissa yet, so here’s the gist: She’s basically a worse version of [scryfall]Civic Wayfinder[/scryfall] (less usable creature class types and can only find forests), but if you have seven lands in play, she flips. The planeswalker version reveals cards of the top of your library. If its a land, you get to play it immediately, otherwise you put it into your hand. The -2 ability produces a legendary 4/4 elemental and the ultimate ability makes six of your lands 6/6 elemental creatures.
The first question here is that is she really better than her Worldwaking counterpart? Probably not. She’s still probably very playable. Getting to seven lands isn’t that hard. There’s plenty of ways to speed that process ([scryfall]Atarka’s Command[/scryfall] and [scryfall]Embodiment of Spring[/scryfall] among others), but I’m guessing the two we might actually want to use are [scryfall]Explosive Vegetation[/scryfall] and [scryfall]Kiora, the Crashing Wave[/scryfall].
If we really ramp into seven lands, we want to do something with that mana. How about [scryfall]Dragonlord Atarka[/scryfall]? Actually we could probably play any of the Dragonlords, because fixing in this deck should be easy enough, but lets not complicate things too much.
There are plenty of ways to build this deck, but I’d go with this one:
[deck]
[creatures]
3 Nissa, Vastwood Seer
4 Rattleclaw Mystic
4 Dragonlord Atarka
2 Hornet Queen
4 Savage Knuckleblade
[/creatures]
[spells]
4 Explosive Vegetation
4 Dig Through Time
2 Stubborn Denial
[/spells]
[planeswalkers]
2 Kiora, the Crashing Wave
2 Xenagos, the Reveler
3 Sarkhan Unbroken
[/planeswalkers]
[lands]
4 Frontier Bivouac
4 Temple of Mystery
4 Temple Abandon
3 Temple of Epiphany
5 Forest
2 Mountain
2 Island
[/lands]
[/deck]
The manabase is a bit problematic, because there’s pretty steep requirements for mana, but at the same time we need enough basics to be able to find them reliably with Nissa and Vegetation.
This is very badly thought-out, but I think there’s a seed of something here.