Llanowar Elves

Into the Flood Maw

Gift a tapped Fish (You may promise an opponent a gift as you cast this spell. If you do, they create a tapped 1/1 blue Fish creature token before its other effects.)
Return target creature an opponent controls to its owner's hand. If the gift was promised, instead return target nonland permanent an opponent controls to its owner's hand.

Forest

Tifa Lockhart

Trample
Landfall — Whenever a land you control enters, double Tifa Lockhart's power until end of turn.

Bristly Bill, Spine Sower

Landfall — Whenever a land you control enters, put a +1/+1 counter on target creature.
{3}{G}{G}: Double the number of +1/+1 counters on each creature you control.

Seedship Impact

Destroy target artifact or enchantment. If its mana value was 2 or less, create a Lander token. (It's an artifact with "{2}, {T}, Sacrifice this token: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.")

Traveling Chocobo

You may look at the top card of your library any time.
You may play lands and cast Bird spells from the top of your library.
If a land or Bird you control entering the battlefield causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Mossborn Hydra

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
This creature enters with a +1/+1 counter on it.
Landfall — Whenever a land you control enters, double the number of +1/+1 counters on this creature.

Snakeskin Veil

Put a +1/+1 counter on target creature you control. It gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Annul

Counter target artifact or enchantment spell.

Ouroboroid

At the beginning of combat on your turn, put X +1/+1 counters on each creature you control, where X is this creature's power.

Secret Identity

Choose one —
• Conceal — Until end of turn, target creature you control becomes a Citizen with base power and toughness 1/1 and gains hexproof.
• Reveal — Until end of turn, target creature you control becomes a Hero with base power and toughness 3/4 and gains flying and vigilance.

Sazh's Chocobo

Landfall — Whenever a land you control enters, put a +1/+1 counter on this creature.