A.T. Robertson Commentary 1 Corinthians 15:54

"But when this corruptible shall have put on incorruption, and this mortal shall have put on immortality, then shall come to pass the saying that is written, Death is swallowed up in victory." — 1 Corinthians 15:54 (ASV)

Shall have put on (ενδυσητα). First aorist middle subjunctive with οταν whenever, merely indefinite future, no futurum exactum, merely meaning, "whenever shall put on," not "shall have put on."

Is swallowed up (κατεποθη). First aorist passive indicative of καταπινω, old verb to drink down, swallow down. Perfective use of κατα- where we say "up," "swallow up." Timeless use of the aorist tense. Paul changes the active voice κατεπιεν in Isa 25:8 to the passive. Death is no longer victory. Theodotion reads the Hebrew verb (bulla, for billa,) as passive like Paul. It is the "final overthrow of the king of Terrors" (Findlay) as shown in Heb 2:15.