Red Potion

The Red Potion is a buff potion which isn't obtainable without inventory editing/hacking. Upon consuming, you get the Burning and Suffocation debuffs.

Trivia

 * It replaced the Soul Scythe in Code.
 * It's a testing item which was changed before the release of the 1.2.2 update to give debuffs instead of buffs.
 * Normally, in some role-playing games, red potions are considered healing potions. Ironically, however, the Red Potion will instead harm the player when consumed.
 * It could also be a reference to Redigit, the main programmer of Terraria.