Like as (hon tropon). “In which manner.” Adverbial accusative and incorporation of the antecedent tropon into the relative clause.
Jannes and Jambres (Iannēs kai Iambrēs). Traditional names of the magicians who withstood Moses (Targum of Jonathan on Exo 7:11).
Withstood (antestēsan). Second aorist active (intransitive) of anthistēmi, to stand against, “they stood against” (with dative Mōusei). Same word used of Elymas in Act 13:8 and repeated here anthistantai (present middle indicative). Paul here pictures the seducers of the gunaikaria above.
Corrupted in mind (katephtharmenoi ton noun). Perfect passive participle of kataphtheirō, old compound, in N.T. only here in critical text. See on 2Co 11:3; 1Ti 6:5 for diaphtheirō. The accusative noun is retained in the passive.
Reprobate (adokimoi). See note on 1Co 9:27; Tit 1:16. They had renounced their trust (pistin) in Christ.