Georgia Code Title 44. Property § 44-14-241

After the levy of the execution on the mortgaged property, the defendant may file his affidavit of illegality, in which affidavit he may avail himself of any defense that he could have set up in an ordinary action upon the demand secured by the mortgage and may show that he is not justly indebted to the plaintiff in the sum claimed in the affidavit of foreclosure. The subsequent proceedings, as to the giving of bond and the trial of the issue made in the case, shall be conducted in the manner prescribed by Code Section 44-14-233.