Mountain

Turn Inside Out

Target creature gets +3/+0 until end of turn. When it dies this turn, manifest dread. (Look at the top two cards of your library. Put one onto the battlefield face down as a 2/2 creature and the other into your graveyard. Turn it face up any time for its mana cost if it's a creature card.)

Firebending Student

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Firebending X, where X is this creature's power. (Whenever this creature attacks, add X {R}. This mana lasts until end of combat.)

Burnout Bashtronaut

Menace
Start your engines! (If you have no speed, it starts at 1. It increases once on each of your turns when an opponent loses life. Max speed is 4.)
{2}: This creature gets +1/+0 until end of turn.
Max speed — This creature has double strike.

Fire Nation Palace

This land enters tapped unless you control a basic land.
{T}: Add {R}.
{1}{R}, {T}: Target creature you control gains firebending 4 until end of turn. (Whenever it attacks, add {R}{R}{R}{R}. This mana lasts until end of combat.)

Slickshot Show-Off

Flying, haste
Whenever you cast a noncreature spell, this creature gets +2/+0 until end of turn.
Plot {1}{R} (You may pay {1}{R} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Combustion Man

Whenever Combustion Man attacks, destroy target permanent unless its controller has Combustion Man deal damage to them equal to his power.

Wild Ride

Target creature gets +3/+0 and gains haste until end of turn.
Harmonize {4}{R} (You may cast this card from your graveyard for its harmonize cost. You may tap a creature you control to reduce that cost by {X}, where X is its power. Then exile this spell.)

Vengeful Possession

Gain control of target creature until end of turn. Untap it. It gains haste until end of turn. You may discard a card. If you do, draw a card.

Pedal to the Metal

Target creature gets +X/+0 and gains first strike until end of turn.

Obliterating Bolt

Obliterating Bolt deals 4 damage to target creature or planeswalker. If that creature or planeswalker would die this turn, exile it instead.

Redirect Lightning

As an additional cost to cast this spell, pay 5 life or pay {2}.
Change the target of target spell or ability with a single target.

Electro, Assaulting Battery

Flying
You don't lose unspent red mana as steps and phases end.
Whenever you cast an instant or sorcery spell, add {R}.
When Electro leaves the battlefield, you may pay {X}. When you do, he deals X damage to target player.