Ashling, the Limitless

Elemental permanent spells you cast from your hand gain evoke {4} as you cast them. (If you cast a spell for its evoke cost, it's sacrificed when it enters.)
Whenever you sacrifice a nontoken Elemental, create a token that's a copy of it. The token gains haste until end of turn. At the beginning of your next end step, sacrifice it unless you pay {W}{U}{B}{R}{G}.

Inferno Project

Trample
This creature enters with X +1/+1 counters on it, where X is the total mana value of instant and sorcery cards in your graveyard.

Havoc Eater

Flying
When this creature enters, for each opponent, goad up to one target creature that opponent controls. Put X +1/+1 counters on this creature, where X is the total power of creatures goaded this way.

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.

Fury

Double strike
When this creature enters, it deals 4 damage divided as you choose among any number of target creatures and/or planeswalkers.
Evoke—Exile a red card from your hand.

Life of the Party

First strike, trample, haste
Whenever this creature attacks, it gets +X/+0 until end of turn, where X is the number of creatures you control.
When this creature enters, if it's not a token, each opponent creates a token that's a copy of it. The tokens are goaded for the rest of the game. (They attack each combat if able and attack a player other than you if able.)

Impulsivity

When this creature enters, you may cast target instant or sorcery card from a graveyard without paying its mana cost. If that spell would be put into a graveyard, exile it instead.
Encore {7}{R}{R} ({7}{R}{R}, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

Ingot Chewer

When this creature enters, destroy target artifact.
Evoke {R} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Heartlash Cinder

Haste
Chroma — When this creature enters, it gets +X/+0 until end of turn, where X is the number of red mana symbols in the mana costs of permanents you control.

Flamebraider

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

Flamekin Harbinger

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