Roil Elemental

Flying
Landfall — Whenever a land you control enters, you may gain control of target creature for as long as you control Roil Elemental.

Bloom Hulk

When Bloom Hulk enters, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Lavakin Brawler

Whenever Lavakin Brawler attacks, it gets +1/+0 until end of turn for each Elemental you control.

Arc Runner

Haste (This creature can attack and {T} as soon as it comes under your control.)
At the beginning of the end step, sacrifice Arc Runner.

Molten Ravager

{R}: Molten Ravager gets +1/+0 until end of turn.

Water Servant

{U}: Water Servant gets +1/-1 until end of turn.
{U}: Water Servant gets -1/+1 until end of turn.

Omnath, Locus of Rage

Landfall — Whenever a land you control enters, 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.

Embodiment of Fury

Trample
Land creatures you control have trample.
Landfall — Whenever a land you control enters, you may have target land you control become a 3/3 Elemental creature with haste until end of turn. It's still a land.

Cloud Elemental

Flying
Cloud Elemental can block only creatures with flying.

Omnath, Locus of the Roil

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

Fiery Hellhound

{R}: Fiery Hellhound gets +1/+0 until end of turn.

Living Tsunami

Flying
At the beginning of your upkeep, sacrifice Living Tsunami unless you return a land you control to its owner's hand.

Vaporkin

Flying
Vaporkin can block only creatures with flying.

Zektar Shrine Expedition

Landfall — Whenever a land you control enters, you may put a quest counter on Zektar Shrine Expedition.
Remove three quest counters from Zektar Shrine Expedition and sacrifice it: Create a 7/1 red Elemental creature token with trample and haste. Exile it at the beginning of the next end step.