Rampant Growth

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

Morska, Undersea Sleuth

You have no maximum hand size.
At the beginning of your upkeep, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")
Whenever you draw your second card each turn, put two +1/+1 counters on Morska.

Jaheira, Friend of the Forest

Tokens you control have "{T}: Add {G}."
Choose a Background (You can have a Background as a second commander.)

Selesnya Signet

Inspiring Statuary

Nonartifact spells you cast have improvise. (Your artifacts can help cast those spells. Each artifact you tap after you're done activating mana abilities pays for {1}.)

Sol Ring

On the Trail

Whenever you draw your second card each turn, you may put a land card from your hand onto the battlefield tapped.

Wilderness Reclamation

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

Simic Signet

Azorius Signet

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.