Become Immense is da best pump NA. It's a pump spell you see in a pack and think "SHOOT that is a big pump, i wonder how many people i can kill with that tonight?"
Then you pick it, and you IMMENSIFY your prophetic flamespeaker in game one, then in game two they doom blade in response to the pump, and you both feel cool for a game.
tldr: if you run no other pump run become immense.
That nissas card looks great for my dargon cube but i think most riptide cubes dont need any more lands once they can cast it. Cool effect though. Dream scenarios include secure the wastes, cyclonic rift, profane command, fireball, and the great aurora, all fun cards to play anyway.
Edit: nissas is also pretty cute with landfall stuff since 3 triggers in a single turn is approaching finite combo range. With the 5-drop pseudo-landfall enchant in play, you get 6 power of bods for your ramp spell.