It sought independence from the Queen Mother of its swarm. Coming to Earth in 1930, it allied with Arnold Bradshaw, recreating Bradshaw's missing arm to seal the deal. Koragatta consumed oil from the fields in Iraq, growing enormous. This enabled it to destroy the still normal sized Vessalak, who had been sent after the traitor.
Koragatta probed the Eleventh Doctor's mind and acquired the knowledge of hyper-dimensional travel. It created a portal and flew through it on Bradshaw's back, taking the Doctor and Omar, a fez maker, as hostages. When Koragatta revealed why it had left its swarm, Bradshaw viewed it as a coward and started fighting it. The Doctor and Omar were freed, with Koragatta and Bradshaw lost in the vortex. (COMIC: A Wing and a Prayer)