They seek out living trees to glean age-old secrets from sap and wood.

Citanul Woodreaders

Kicker {2}{G} (You may pay an additional {2}{G} as you cast this spell.)
When this creature enters, if it was kicked, draw two cards.

Time Spiral Remastered

Kicker {2}{G} (You may pay an additional {2}{G} as you cast this spell.)
When Citanul Woodreaders enters the battlefield, if it was kicked, draw two cards.

The List

Duel Decks: Nissa vs. Ob Nixilis

Modern Masters

Planar Chaos

Kicker {2}{G} (You may pay an additional {2}{G} as you play this spell.)
When Citanul Woodreaders comes into play, if the kicker cost was paid, draw two cards.

If a card or token enters as a copy of a permanent, the new permanent isn't kicked, even if the original was.

If a spell's kicker cost was paid, the spell is "kicked."

If you copy a kicked spell on the stack, the copy is also kicked. If the copied spell is a permanent spell, the token the copy of that spell becomes when it enters is also kicked.

If you put a permanent with a kicker ability onto the battlefield without casting it, you can't kick it.

The kicker ability doesn't let you pay a kicker cost more than once.

To determine a spell's total cost, start with the mana cost (or an alternative cost if another card's effect allows you to pay one instead), add any cost increases (such as kicker), then apply any cost reductions. The spell's mana value remains unchanged, no matter what the total cost to cast it was.