Doubling Cube

{3}, {T}: Double the amount of each type of unspent mana you have.

Forest

Wilderness Reclamation

At the beginning of your end step, untap all lands you control.

Llanowar Visionary

When this creature enters, draw a card.
{T}: Add {G}.

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.

Llanowar Tribe

Llanowar Elves

Elvish Mystic

Moss Diamond

This artifact enters tapped.
{T}: Add {G}.

Omnath, Locus of Mana

You don't lose unspent green mana as steps and phases end.
Omnath gets +1/+1 for each unspent green mana you have.

Fyndhorn Elves

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Giant Ankheg

Trample
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
Other creatures you control have trample and ward {2}.