Vow of Retaliation (反撃の誓い,Hangeki no chikai?) is the 91st chapter of the Berserk manga series, written and illustrated by Kentaro Miura.
Guts recognizes the Skull Knight from their first and only meeting, on the night Guts left the Hawks. He hears the grass begin to violently rustle behind him.
The Skull Knight tosses Guts his sword, an odd object in that it has sharp spikes in its hilt and is oddly ornate. Despite hurting his hand as he swings it, Guts wields it against the things rising from the grass. The Skull Knight explains that they are the spirits of the dead who, like other creatures of darkness, will be drawn to Guts' Brand of Sacrifice and desire warm, living bodies to possess.
The spirits have trapped Guts, clinging to his ankles as they enter his body to possess him. But Guts forces the specters out of him through sheer force of will. As he swings the sword around, he moves his left arm in conjunction with his right, despite the fact that it ends in a stump just below the elbow. He is unused to fighting with only one arm. The Skull Knight tells Guts not to lose focus, as the spirits will not cease attacking. He says that Guts' life will now consist of constantly fighting such spirits, which cannot be perceived by others, and other creatures of darkness. Thanks to the Brand, Guts exists in the Interstice, and thus he can see and interact with both the living and the dead.
Guts silences the Skull Knight with a yell, disliking all the mentions of "destiny", "sacrifices", and the like. He tells the Skull Knight that this is just like war - fighting to be the last man standing. As he swings the sword around, causing the spirits to fade, he loudly declares war against the Apostles, who killed all his friends, and the other God Hand who command them, and Griffith.
The spirits Guts has not yet dispatched slowly fade into the night. Guts wonders whether they have given up, but the Skull Knight informs him that they have simply found another body to take over. Suddenly remembering Casca, who also now resides in the Interstice, Guts points the sword at the Skull Knight, intending to use his horse to reach her. The Skull Knight grabs Guts' outstretched hand and lifts him up onto his giant horse. He tells Guts to hang on, and they begin to move in Casca's direction.