Lightning Elemental

Haste (This creature can attack and {T} as soon as it comes under your control.)

Lightning Shrieker

Flying, trample, haste
At the beginning of the end step, Lightning Shrieker's owner shuffles it into their library.

Weaver of Lightning

Reach (This creature can block creatures with flying.)
Whenever you cast an instant or sorcery spell, Weaver of Lightning deals 1 damage to target creature an opponent controls.

Lightning-Core Excavator

{5}, {T}, Sacrifice Lightning-Core Excavator: It deals 3 damage to any target.

Lightning Phoenix

Flying, haste
Lightning Phoenix can't block.
At the beginning of your end step, if an opponent was dealt 3 or more damage this turn, you may pay {R}. If you do, return Lightning Phoenix from your graveyard to the battlefield.

Homing Lightning

Homing Lightning deals 4 damage to target creature and each other creature with the same name as that creature.

Thriving Bluff

Thriving Bluff enters tapped. As it enters, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

Living Lightning

When Living Lightning dies, return target instant or sorcery card from your graveyard to your hand.

Mountain

Lightning Axe

As an additional cost to cast this spell, discard a card or pay {5}.
Lightning Axe deals 5 damage to target creature.

Lightning Visionary

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Lightning Diadem

Enchant creature
When Lightning Diadem enters, it deals 2 damage to any target.
Enchanted creature gets +2/+2.