Prevent all combat damage that would be dealt this turn.

Killer Bees

Flying
{G}: Killer Bees gets +1/+1 until end of turn.

Dark Heart of the Wood

Shanodin Dryads

Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)

Magical Hack

Change the text of target spell or permanent by replacing all instances of one basic land type with another. (For example, you may change "swampwalk" to "plainswalk." This effect lasts indefinitely.)

Living Lands

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

Aspect of Wolf

Enchant creature
Enchanted creature gets +X/+Y, where X is half the number of Forests you control, rounded down, and Y is half the number of Forests you control, rounded up.

Fastbond

You may play any number of lands on each of your turns.
Whenever you play a land, if it wasn't the first land you played this turn, Fastbond deals 1 damage to you.

Bayou

Giant Spider

Reach (This creature can block creatures with flying.)

Giant Growth

Target creature gets +3/+3 until end of turn.

Tropical Island

Cockatrice

Flying
Whenever Cockatrice blocks or becomes blocked by a non-Wall creature, destroy that creature at end of combat.

Thelonite Druid

{1}{G}, {T}, Sacrifice a creature: Forests you control become 2/3 creatures until end of turn. They're still lands.

Scarwood Hag

{G}{G}{G}{G}, {T}: Target creature gains forestwalk until end of turn. (It can't be blocked as long as defending player controls a Forest.)
{T}: Target creature loses forestwalk until end of turn.

Forest

Erhnam Djinn

At the beginning of your upkeep, target non-Wall creature an opponent controls gains forestwalk until your next upkeep. (It can't be blocked as long as defending player controls a Forest.)