Whenever Lightseeker Nymph perseveres, search your library for a basic land card, put it onto the battlefield tapped, then shuffle. (A creature perseveres when it survives damage.)
Not every child of the forest feels the need to stay one.
Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.) Whenever you cast a white, blue, black, or red spell, add one mana of any color that spell isn't.
Primal {1}{G}(During your turn, you may cast this spell for {1}{G} instead of playing a land.) Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.
Creatures with power less than Sneaking Peak's power can't block it. At the beginning of your end step, if Sneaking Peak didn't attack this turn, put a +1/+1 counter on it.
Primal {2}{U}{U}(During your turn, you may cast this spell for {2}{U}{U} instead of playing a land.) Whenever Tangleveil Mystic deals combat damage to a player, draw cards equal to the number of cards in your hand.