Mountain

Flamekin Harbinger

When Flamekin Harbinger enters, you may search your library for an Elemental card, reveal it, then shuffle and put that card on top.

Overgrowth Elemental

When Overgrowth Elemental enters, put a +1/+1 counter on another target Elemental you control.
Whenever another creature you control dies, you gain 1 life. If that creature was an Elemental, put a +1/+1 counter on Overgrowth Elemental.

Forest

Smokebraider

{T}: Add two mana in any combination of colors. Spend this mana only to cast Elemental spells or activate abilities of Elementals.

Risen Reef

Whenever Risen Reef or another Elemental you control enters, look at the top card of your library. If it's a land card, you may put it onto the battlefield tapped. If you don't put the card onto the battlefield, put it into your hand.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Chandra, Acolyte of Flame

0: Put a loyalty counter on each red planeswalker you control.
0: Create two 1/1 red Elemental creature tokens. They gain haste. Sacrifice them at the beginning of the next end step.
−2: You may cast target instant or sorcery card with mana value 3 or less from your graveyard. If that spell would be put into your graveyard, exile it instead.

Fecund Greenshell

Reach
As long as you control ten or more lands, creatures you control get +2/+2.
Whenever Fecund Greenshell or another creature you control with toughness greater than its power enters, look at the top card of your library. If it's a land card, you may put it onto the battlefield tapped. Otherwise, put it into your hand.

Secluded Courtyard

As this land enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type or activate an ability of a creature source of the chosen type.

Island

Thunderkin Awakener

Haste
Whenever Thunderkin Awakener attacks, choose target Elemental creature card in your graveyard with toughness less than Thunderkin Awakener's toughness. Return that card to the battlefield tapped and attacking. Sacrifice it at the beginning of the next end step.

Domri's Ambush

Put a +1/+1 counter on target creature you control. Then that creature deals damage equal to its power to target creature or planeswalker you don't control.

Scampering Scorcher

When Scampering Scorcher enters, create two 1/1 red Elemental creature tokens. Elementals you control gain haste until end of turn. (They can attack and {T} this turn.)

Incandescent Soulstoke

Other Elemental creatures you control get +1/+1.
{1}{R}, {T}: You may put an Elemental creature card from your hand onto the battlefield. That creature gains haste until end of turn. Sacrifice it at the beginning of the next end step.

Creeping Trailblazer

Other Elementals you control get +1/+0.
{2}{R}{G}: Creeping Trailblazer gets +1/+1 until end of turn for each Elemental you control.

Chandra, Novice Pyromancer

+1: Elementals you control get +2/+0 until end of turn.
−1: Add {R}{R}.
−2: Chandra, Novice Pyromancer deals 2 damage to any target.

Unclaimed Territory

As Unclaimed Territory enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type.