Life and Limb

All Forests and all Saprolings are 1/1 green Saproling creatures and Forest lands in addition to their other types. (They're affected by summoning sickness.)

Natural Affinity

All lands become 2/2 creatures until end of turn. They're still lands.

Crawlspace

No more than two creatures can attack you each combat.

Bear Umbra

Enchant creature
Enchanted creature gets +2/+2 and has "Whenever this creature attacks, untap all lands you control."
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Aura Mutation

Destroy target enchantment. Create X 1/1 green Saproling creature tokens, where X is that enchantment's mana value.

Yasharn, Implacable Earth

When Yasharn enters, search your library for a basic Forest card and a basic Plains card, reveal those cards, put them into your hand, then shuffle.
Players can't pay life or sacrifice nonland permanents to cast spells or activate abilities.

Living Lands

All Forests are 1/1 creatures that are still lands.

Secure the Wastes

Create X 1/1 white Warrior creature tokens.

Reverence

Creatures with power 2 or less can't attack you.

Nature's Revolt

All lands are 2/2 creatures that are still lands.