Skizzik

Kicker {R} (You may pay an additional {R} as you cast this spell.)
Trample, haste
At the beginning of the end step, if this creature wasn't kicked, sacrifice it.

Sol Ring

Chain Lightning

Chain Lightning deals 3 damage to any target. Then that player or that permanent's controller may pay {R}{R}. If the player does, they may copy this spell and may choose a new target for that copy.

Slith Firewalker

Haste
Whenever this creature deals combat damage to a player, put a +1/+1 counter on it.

Blistering Firecat

Trample, haste
At the beginning of the end step, sacrifice this creature.
Morph {R}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Mountain

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Ball Lightning

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Haste (This creature can attack and {T} as soon as it comes under your control.)
At the beginning of the end step, sacrifice this creature.

Fireball

This spell costs {1} more to cast for each target beyond the first.
Fireball deals X damage divided evenly, rounded down, among any number of targets.