Omnath, Locus of the Roil

When Omnath, Locus of the Roil enters the battlefield, it deals damage to any target equal to the number of Elementals you control.
Landfall — Whenever a land enters the battlefield under your control, put a +1/+1 counter on target Elemental you control. If you control eight or more lands, draw a card.

Titania, Protector of Argoth

When Titania, Protector of Argoth enters the battlefield, return target land card from your graveyard to the battlefield.
Whenever a land you control is put into a graveyard from the battlefield, create a 5/3 green Elemental creature token.

Mountain

Lotus Cobra

Landfall — Whenever a land enters the battlefield under your control, add one mana of any color.

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Akoum Hellhound

Landfall — Whenever a land enters the battlefield under your control, Akoum Hellhound gets +2/+2 until end of turn.

Brushfire Elemental

Haste
Brushfire Elemental can't be blocked by creatures with power 2 or less.
Landfall — Whenever a land enters the battlefield under your control, Brushfire Elemental gets +2/+2 until end of turn.

Foundation Breaker

When Foundation Breaker enters the battlefield, you may destroy target artifact or enchantment.
Evoke {1}{G} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters the battlefield.)

Flamekin Harbinger

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

Omnath, Locus of Rage

Landfall — Whenever a land enters the battlefield under your control, create a 5/5 red and green Elemental creature token.
Whenever Omnath, Locus of Rage or another Elemental you control dies, Omnath deals 3 damage to any target.

Forest

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Island

Harrow

As an additional cost to cast this spell, sacrifice a land.
Search your library for up to two basic land cards, put them onto the battlefield, then shuffle.

Omnath, Locus of Creation

When Omnath, Locus of Creation enters the battlefield, draw a card.
Landfall — Whenever a land enters the battlefield under your control, you gain 4 life if this is the first time this ability has resolved this turn. If it's the second time, add {R}{G}{W}{U}. If it's the third time, Omnath deals 4 damage to each opponent and each planeswalker you don't control.

Plains

Risen Reef

Whenever Risen Reef or another Elemental enters the battlefield under your control, 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.

Fabled Passage

{T}, Sacrifice Fabled Passage: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.