Rootless Yew

When Rootless Yew dies, search your library for a creature card with power or toughness 6 or greater, reveal it, put it into your hand, then shuffle.

Unstoppable Ash

Trample
Champion a Treefolk or Warrior (When this enters the battlefield, sacrifice it unless you exile another Treefolk or Warrior you control. When this leaves the battlefield, that card returns to the battlefield.)
Whenever a creature you control becomes blocked, it gets +0/+5 until end of turn.

Phytohydra

If damage would be dealt to Phytohydra, put that many +1/+1 counters on it instead.

Kirri, Talented Sprout

Other Plants and Treefolk you control get +2/+0.
At the beginning of your postcombat main phase, return target Plant, Treefolk, or land card from your graveyard to your hand.

Treebeard, Gracious Host

Trample, ward {2}
When Treebeard, Gracious Host enters the battlefield, create two Food tokens.
Whenever you gain life, put that many +1/+1 counters on target Halfling or Treefolk.

Ulvenwald Observer

Whenever a creature you control with toughness 4 or greater dies, draw a card.

Mirrorwood Treefolk

{2}{R}{W}: The next time damage would be dealt to Mirrorwood Treefolk this turn, that damage is dealt to any target instead.

Wall of Roots

Defender
Put a -0/-1 counter on Wall of Roots: Add {G}. Activate only once each turn.

Seedguide Ash

When Seedguide Ash dies, you may search your library for up to three Forest cards, put them onto the battlefield tapped, then shuffle.