Acid Hydra enters with X +1/+1 counters on it.
Drop — When Acid Hydra enters, search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle. Then return that creature to your hand unless you didn't cast any creature spells during your last turn.

You may cast target instant or sorcery card from your graveyard this turn. If that card would be put into your graveyard this turn, exile it instead.
Add one mana of any color for each time you've amped it up this turn.

This spell costs {1} less to cast for each Elemental you control.
Haste

At the beginning of combat on your turn, Thrill of the Trendchase becomes a copy of a creature on the battlefield chosen at random until end of turn, except it's a 5/5 red Elemental with flying and haste and isn't legendary if the chosen creature is legendary.

Untap target creature and gain control of it until end of turn. That creature gains haste until end of turn.

{1}{VP}{R}, Discard a card: Draw a card.

Whenever you amp it up, Spirit of the Crowd gets +1/+1 and gains trample until end of turn.

Haste
At the beginning of your end step, if a creature died this turn, put a +1/+1 counter on Soundforged Tyrant.

Menace
{VP}{VP}: Sizzling Star gets +1/+0 until end of turn.

{3}, {T}, Sacrifice Scorching Illuminator: Return target instant or sorcery card from your graveyard to your hand. Add one mana of any color.

Target creature gets +1/+0 and gains first strike until end of turn. It gets an additional +2/+0 until end of turn for each time you've amped it up this turn.

When Riotous Rockers enters, it deals 3 damage to up to one target that was dealt damage this turn.

At the beginning of combat on your turn, you may pay {1}. If you do, create a 1/1 red and green Elemental creature token. It gains haste. Sacrifice it at end of combat.

Whenever you amp it up, Pyrote Technician deals 2 damage to each opponent.

Haste
{T}, Sacrifice Pyrote Entity: It deals 1 damage to any target.

As Prodigious Hater enters, look at an opponent's hand, then choose a nonland card name.
Whenever an opponent casts a spell with the chosen name, Prodigious Hater deals 3 damage to that player.

Exile the top two cards of your library. Until the end of your next turn, you may play those cards. Cards exiled this way cost {2} less to cast if they're instants, sorceries, or Elementals.

When Photonic Cobra dies, create a 1/1 red and green Elemental creature token.

Create three 1/1 red and green Elemental creature tokens.

[+1]: Exile the top card of your library. You may play it this turn. If that card doesn't share a name with a permanent you control or a card in your graveyard, add {R}{R}.
[–2]: Gain control of target creature until end of turn. Untap that creature. It gains haste and menace until end of turn.
[–6]: You get an emblem with “Whenever you amp it up, this emblem deals 2 damage to any target.”

Creatures you control get +2/+0 until end of turn. Up to one target Elemental you control gains first strike until end of turn.

Exile the top three cards of your library. You may play up to two of those cards this turn.

Lightvein Arrow deals 3 damage to any target. Scry 1.

Reach
{VP}{VP}{VP}: Laser Technician deals 1 damage to target player, planeswalker, or creature with flying.

{3}{R}{R}, Exile Indulge the Fifth Encore from your hand: At the beginning of your next upkeep, you may cast Indulge the Fifth Encore from exile without paying its mana cost. Activate only as a sorcery.
Add {W}{U}{B}{R}{G}. Until end of turn, you don't lose this mana as steps and phases end.