Aggressive Mammoth

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Other creatures you control have trample.

Yavimaya Hollow

{T}: Add {C}.
{G}, {T}: Regenerate target creature.

Call of the Herd

Create a 3/3 green Elephant creature token.
Flashback {3}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Selvala's Charge

Parley — Each player reveals the top card of their library. For each nonland card revealed this way, you create a 3/3 green Elephant creature token. Then each player draws a card.

Prized Elephant

Prized Elephant gets +1/+1 as long as you control a Forest.
{G}: Prized Elephant gains trample until end of turn. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Sapseep Forest

({T}: Add {G}.)
Sapseep Forest enters tapped.
{G}, {T}: You gain 1 life. Activate only if you control two or more green permanents.

Selvala, Explorer Returned

Parley — {T}: Each player reveals the top card of their library. For each nonland card revealed this way, add {G} and you gain 1 life. Then each player draws a card.

Gaea's Cradle

{T}: Add {G} for each creature you control.

Crazed Armodon

{G}: Crazed Armodon gets +3/+0 and gains trample until end of turn. Destroy Crazed Armodon at the beginning of the next end step. Activate only once each turn.

Elephant Graveyard

{T}: Add {C}.
{T}: Regenerate target Elephant.

Southern Elephant

Wild Elephant

Arctic Treeline

({T}: Add {G} or {W}.)
Arctic Treeline enters tapped.

Selvala's Stampede

Council's dilemma — Starting with you, each player votes for wild or free. Reveal cards from the top of your library until you reveal a creature card for each wild vote. Put those creature cards onto the battlefield, then shuffle the rest into your library. You may put a permanent card from your hand onto the battlefield for each free vote.

Sandsteppe Mastodon

Reach
When Sandsteppe Mastodon enters, bolster 5. (Choose a creature with the least toughness among creatures you control and put five +1/+1 counters on it.)

Forest

Trumpeting Herd

Create a 3/3 green Elephant creature token.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Parallel Lives

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Kazandu Valley

Kazandu Valley enters tapped.
{T}: Add {G}.

Kazandu Mammoth

Landfall — Whenever a land you control enters, Kazandu Mammoth gets +2/+2 until end of turn.

Kazandu Mammoth // Kazandu Valley

Snow-Covered Forest

Kazandu Tuskcaller

Level up {1}{G} ({1}{G}: Put a level counter on this. Level up only as a sorcery.)
LEVEL 2-5
1/1
{T}: Create a 3/3 green Elephant creature token.
LEVEL 6+
1/1
{T}: Create two 3/3 green Elephant creature tokens.

Savannah

Trained Armodon

Battle Mammoth

Trample
Whenever a permanent you control becomes the target of a spell or ability an opponent controls, you may draw a card.
Foretell {2}{G}{G} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

War Mammoth

Elephant Guide

Enchant creature
Enchanted creature gets +3/+3.
When enchanted creature dies, create a 3/3 green Elephant creature token.