They both knew only one of them would walk away.

High Noon

Each player can't cast more than one spell each turn.
{4}{R}, Sacrifice High Noon: It deals 5 damage to any target.

Outlaws of Thunder Junction

Outlaws of Thunder Junction Promos

If you cast High Noon, you’ve already cast at least one spell that turn (High Noon itself) so you won’t be able to cast any more spells until the next turn. If High Noon enters the battlefield on a turn where you haven’t cast any spells, you’ll be able to cast one spell that turn.

If you cast a spell that was countered, you can’t cast another spell during the same turn while High Noon is on the battlefield.