Ivy Lane Denizen

Whenever another green creature you control enters, put a +1/+1 counter on target creature.

Coat of Arms

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)

Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Dawntreader Elk

{G}, Sacrifice Dawntreader Elk: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Forest

Broken Bond

Destroy target artifact or enchantment. You may put a land card from your hand onto the battlefield.

Muraganda Petroglyphs

Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.

Sylvan Anthem

Green creatures you control get +1/+1.
Whenever a green creature you control enters, scry 1.

Echoing Courage

Target creature and all other creatures with the same name as that creature get +2/+2 until end of turn.

Farhaven Elf

When Farhaven Elf enters, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Llanowar Elves

Herd Baloth

Whenever one or more +1/+1 counters are put on Herd Baloth, you may create a 4/4 green Beast creature token.

Harmonize

Sylvan Scrying

Search your library for a land card, reveal it, put it into your hand, then shuffle.

Primeval Protector

This spell costs {1} less to cast for each creature your opponents control.
When Primeval Protector enters, put a +1/+1 counter on each other creature you control.