Multiverse Black Lightning is a three-star base hero that specializes in hampering opponent specials; both increasing power cost and healing from power drain specials similar to Energized Starfire.
He can be received by Arena rewards and a 2% chance of getting him in the Shared Realities chest. He can also be found in the Multiverse Power Up Chest with unknown probability. His most recent addition to a chest is in the Vigilante Chest, which has a 3% chance of yielding him.
His passive does affect Special block abilities, causing to drain power more rapidly. This makes it extremely difficult to use them against his team, as special blocks are most efficient when you can turn it on and off flexibly at will.
While your power cost only goes up when used against him or his Multiverse teammates, the increased cost will still be active when you're fighting non-Multiverse teammates.
Supermoves tend to be effective against him, as you can only use them once anyway and it can't be affected by the increased power cost.
Electric Cage is difficult to fight against. Not only does it prevent you from moving, you also cannot tag to escape it while trapped.