The Yellowjacket Suit was a powered suit created by Darren Cross that used his version of Hank Pym’s Pym Particles.
The suit was created by Darren Cross who used the Ant-Man Suit technology as a base. The partly mechanized suit was designed to be weaponized and more advanced version of Hank Pym’s suit. The mechanisms in some of the metallic parts part of the suit may possibly be used for resilience or strength enhancement. It was designed with mechanical appendages on its back with the pair above the other being able to fire beams of energy.
Cross would later put on the suit in order to deal with Ant-Man. After a long and difficult fight, the suit was sabotaged by Lang, who shrunk between the molecules of the solid titanium armor to reach and destroy the suit’s circuitry and inner mechanisms. The suit’s now unstable shrinking function caused Cross to be crushed in the suit, imploding his body into nothingness, effectively killing himself and destroying the suit.
Darren Cross was the protégé of Hank Pym who became the CEO of Cross Technologies. His obsession with Pym’s former design of the Ant-Man Suit led to him replicating his Mentor’s formula which he intended to sell to the terrorist organization HYDRA. Using his own version of the suit, the Yellowjacket, he tried to fulfill the transaction, but he was stopped and killed by Pym, Hope van Dyne and Scott Lang.