Scouting Trek

Search your library for any number of basic land cards, reveal those cards, then shuffle and put them on top.

Terastodon

When Terastodon enters, you may destroy up to three target noncreature permanents. For each permanent put into a graveyard this way, its controller creates a 3/3 green Elephant creature token.

War Mammoth

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.)

Frontier Mastodon

Ferocious — Frontier Mastodon enters with a +1/+1 counter on it if you control a creature with power 4 or greater.

Wild Elephant

Woolly Loxodon

Morph {5}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

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.)

Honey Mammoth

When Honey Mammoth enters, you gain 4 life.

Exploration

You may play an additional land on each of your turns.

Aggressive Mammoth

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

Rabid Elephant

Whenever Rabid Elephant becomes blocked, it gets +2/+2 until end of turn for each creature blocking it.

Forest

Thorn Mammoth

Trample
Whenever Thorn Mammoth or another creature you control enters, Thorn Mammoth fights up to one target creature you don't control.

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.)

Metamorphic Wurm

Threshold — Metamorphic Wurm gets +4/+4 as long as seven or more cards are in your graveyard.