Toph, Greatest Earthbender

When Toph enters, earthbend X, where X is the amount of mana spent to cast her.
Land creatures you control have double strike.

Arcane Signet

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

Gruul Signet

Talisman of Impulse

{T}: Add {C}.
{T}: Add {R} or {G}. This artifact deals 1 damage to you.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

Sol Ring

Bumi, Unleashed

Trample
When Bumi enters, earthbend 4.
Whenever Bumi deals combat damage to a player, untap all lands you control. After this phase, there is an additional combat phase. Only land creatures can attack during that combat phase.

Toph, Earthbending Master

Landfall — Whenever a land you control enters, you get an experience counter.
Whenever you attack, earthbend X, where X is the number of experience counters you have. (Target land you control becomes a 0/0 creature with haste that's still a land. Put X +1/+1 counters on it. When it dies or is exiled, return it to the battlefield tapped.)

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice this artifact: Draw a card.

Ashaya, Soul of the Wild

Ashaya's power and toughness are each equal to the number of lands you control.
Nontoken creatures you control are Forest lands in addition to their other types. (They're still affected by summoning sickness.)