The Avengers (1963) #195

The Avengers surround the Solomon Institute but cannot enter without a search warrant, so they recruit Yellowjacket and Ant-Man, who invade the premises in search of the Wasp.

To their surprise, the two tiny adventurers discover the facility to be a front for a training academy for costumed criminals’ henchmen. Finding the Wasp an unconscious prisoner, they revive her, but then all three are captured by Dr. Pernell Solomon, head of the Institute, and his men.

Solomon reveals that Selbe, who resembles a younger version of himself, is actually a clone rapidly aged to adulthood and the planned donor for a heart transplant, since Solomon himself has both a weak heart and a rare blood type and thus requires a virtually identical donor.

Yellowjacket, Ant-Man, and the Wasp overpower Solomon and his aides and rush to free Selbe. They no sooner locate his cell, however, than they are ambushed by the newly arrived true master of the academy, the bizarrely costumed Taskmaster.

The Marvel Comics Database.