Have

Flash Flood

Choose one —
• Destroy target red permanent.
• Return target Mountain to its owner's hand.

Suffocation

Cast this spell only if you were dealt damage this turn by a red instant or sorcery spell.
Suffocation deals 4 damage to the controller of the last red instant or sorcery spell that dealt damage to you this turn.
Draw a card at the beginning of the next turn's upkeep.

Blue Elemental Blast

Choose one —
• Counter target red spell.
• Destroy target red permanent.

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Circle of Protection: Red

{1}: The next time a red source of your choice would deal damage to you this turn, prevent that damage.

Plains

Sky Diamond

Hydroblast

Choose one —
• Counter target spell if it's red.
• Destroy target permanent if it's red.

Prodigal Sorcerer

{T}: Prodigal Sorcerer deals 1 damage to any target.

Marble Diamond

Marble Diamond enters tapped.
{T}: Add {W}.

Island

Justice

At the beginning of your upkeep, sacrifice Justice unless you pay {W}{W}.
Whenever a red creature or spell deals damage, Justice deals that much damage to that creature's or spell's controller.

Psychic Venom

Enchant land
Whenever enchanted land becomes tapped, Psychic Venom deals 2 damage to that land's controller.