Sol Ring

Marath, Will of the Wild

Marath, Will of the Wild enters with a number of +1/+1 counters on it equal to the amount of mana spent to cast it.
{X}, Remove X +1/+1 counters from Marath: Choose one —
• Put X +1/+1 counters on target creature. X can't be 0.
• Marath deals X damage to any target. X can't be 0.
• Create an X/X green Elemental creature token. X can't be 0.

Chord of Calling

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Snake Umbra

Enchant creature
Enchanted creature gets +1/+1 and has "Whenever this creature deals damage to an opponent, you may draw a card."
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Eternal Witness

When Eternal Witness enters, you may return target card from your graveyard to your hand.

Hardened Scales

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Basilisk Collar

Equipped creature has deathtouch and lifelink.
Equip {2}

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Cathars' Crusade

Whenever a creature you control enters, put a +1/+1 counter on each creature you control.

Eladamri's Call

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

Ashnod's Altar

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Ivy Lane Denizen

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

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Crystalline Crawler

Converge — Crystalline Crawler enters with a +1/+1 counter on it for each color of mana spent to cast it.
Remove a +1/+1 counter from Crystalline Crawler: Add one mana of any color.
{T}: Put a +1/+1 counter on Crystalline Crawler.