Kong: The Animated Series - Season 1 Episode 9 Curse of the Great Dragon

In England, De La Porta forces a Druid Priest, Dr. MacKay, to agree to help him use ancient Druid ceremonies to unlock the powers of a Primal Stone. Kong and his friends travel to England to stop them. Merging with a wild boar, De La Porta dukes it out with Kong, forcing our heroes to retreat. The battle resumes at Stonehenge where MacKay is unleashing the power of the Stone. Merged as a fantastic cat/scorpion hybrid--the manticore--De La Porta holds Kong at bay until the Stone opens up a vortex into Infinity. Kong is nearly sucked into the vortex, but Jason merges with him and becomes Mega-Kong, escaping the vortex and defeating De La Porta.