Hey, am considering building this deck as well so a +1 from me and i look forward to seeing this deck evolve. For starters one auto include in this deck is Fertilid allowing you to get a lot of lands with the commander. Everything from here on out depend on which way you want to build the deck. Me personnaly would run it very land focus as the elemental pay-off is quite meh without big land drop anyway. I see you are running the big land pay-offs ( Avenger of Zendikar , Rampaging Baloths )but no real big land drops. Besides that i see some very cool lands but maybe not enough lands for a landsdeck. I aim for 40 lands in a lands deck. To get 'big' land drops there is a pretty easy package starting with Scapeshift this is a all in one card getting you your good lands while allowing for some exlposiveness with the lands next to that wee have Splendid Reclamation with Zuran Orb or The Mending of Dominaria . An other good general card in this deck is Budoka Gardener as it makes elementals. With cards like Trade Routes and Retreat to Coralhelm you can also get infinite landfall triggers with the gardeners. Getting a Crucible of Worlds is higly worth it, it makes decks like these so much better.

I am not really versed in the elemental part of it all but there are some lords already printed Incandescent Soulstoke . Besides that i think that the nissa you already have in your deck is perfect for this deck.

Some more general remarks come in the ramp base. As a land deck you might want to consider getting some if not all of the signets and stone out of there and replacing it with some land ramp. I have a tatyova deck on here which is quite budget so you might get some inspiration from there.