Batman Vol.1 #618
Jason Todd is ready to slit Robin's throat, and accuses him of being a "pretender" to the role. Catwoman arrives and dives down on top of him, freeing Robin from Jason's grip. With the Boy Wonder out of danger, Batman takes the opportunity to engage Jason directly. Batman stabs him in the leg with a Batarang, then delivers a crushing punch to the solar plexus.
The two continue to trade blows, until Jason takes to higher ground. Jason confesses to cutting the batline, which caused the Dark Knight to plummet nearly to his death in Crime Alley. Batman begins to suspect that this may not actually be Jason Todd. After several more minutes of intense fighting, Batman wins out over him. Jason's features dissolve into a river of clay that slips through Batman's fingers. Jason was actually Clayface in disguise.
Estimated Condition: VF/NM