Tonic of Twin Wounds (Kingdom Aflame, Standard Card, #23) is an uncommon Potion card with 0 attack and 0 defense.
Card Effect
Potion: You and your opponent each gain 1 Damage Counter.
Card Description
"With this drink, enemy mine, we are linked by the threads of fate. Though I alone walk among the swords, we shall bleed together." -- The Forever Soldier