The actor, who plays the warrior Gannicus, told TV Guide that tonight's finale will contain "the biggest fight... ever attempted on this show".
"There's a lot [of people involved]," he explained. "It varies [but] it took us around eight days to film. It was a huge endeavour and it's definitely the biggest action sequence we've ever put together on Spartacus."
Clare also revealed that the instalment will see Gannicus "reconnecting with himself" following the death of his friend Melitta (Marisa Ramirez) in the previous episode.
"It's really about [Gannicus] reconnecting with his friend [and Melitta's husband] Doctor Oenomaus," he said. "Having the friendship and that love pull him out of all the circumstances that have come before."
He added: "In the last few episodes, he's been very disengaged from himself, from the world and from his friendships."
Spartacus: Gods of the Arena concludes tonight at 10/9c on Starz.