Fan Casting Spot in Marvel animated comic show

As a scientist working for the Kingpin, Dr. Ohnn was assigned to reproduce the radiation levels of the vigilante Cloak to find a way to artificially mimic his powers. Working late one night, he succeeded, creating a solid black circular portal. In doing so, however, the drain on the city's power became so great, a blackout washed over the city, causing the portal to shimmer and destabilize. Fearful of losing a once in a lifetime opportunity, Ohnn stepped into it; the shock of the transition caused him to pass out. He awoke floating weightlessly in a dimension which he initially assumed was Cloak's dark dimension.