Once attached to someones skin, the Counter Rune shows the symbol of two strikes: One that appears to be evaded, and another that avoids the first strike, takes a turn and hits back. And that is exactly what this rune will cause in battle. Easily mistaken as some kind of "strike-back" factor, it actually protects the wielder, letting him evade a single, physical attack and then goes instantaneous for a counterstrike, based on the users attack power. The occurance of this evade-and-counter effect is based on the natual counter rate of the character holding this rune. Hence it is logical to equip characters with initially high attack and skill/technique abilities with the Counter Rune. Think about good combinations with the Firefly Rune in order to set a power tank or the Wall Rune, putting someone to nearly invulnerable defense.
The Counter Rune was introduced in Suikoden I, when most players found the first instance of a Counter crystal in Lepant's Mansion in Kouan, normally attaching it to Viktor, Tai Ho or probably Camille. More could be easily bought at the following village in the Great Forest. Every game in the series so far, includes the Counter Rune as a common item (except Suikoden 2, where for unknown reasons only Pesmerga starts with it and a second one can be won from the Guardian Deity event), letting the player decide how frequently bringing this handy item to good use. It is considered as one of the more popular effect runes. - Celes