Original
Chain Lightning: When Beta Ray Biill targets a character with a ranged combat attack, he may target an additional character within 3 squares and line of fire from the first character. If he does, instead of normal damage deal the first character 3 damage and the second character 2 damage if hit. The second character does not have to be within Beta Ray Bill's range or line of fire.

Cosmic Storm and Eclipse: Opposing characters within 6 squares possessing the symbol modify their speed and attack values by -1. Friendly characters within 6 squares that can use Stealth have lines of fire drawn to them blocked when it's not your turn.

Errata
Chain Lightning: When Beta Ray Biill targets a character with a ranged combat attack, he may target an additional character within 3 squares and line of fire from the first character. If he does, instead of normal damage deal the first character 3 damage and the second character 2 damage if hit. The second character does not have to be within Beta Ray Bill's range or line of fire.

If a character has line of fire blocked to it because of Cosmic Storm and Eclipse, can my Ultimate/Avengers Initiative/Superman TA character draw line of fire still?
No. Normally Stealth will turn a hindered line of fire into a blocked line of fire, so game effects that would ignore hindering terrain for line of fire purposes (like the Ultimates TA), would not be hindered and couldn't be turned into a blocked line of fire. This special power does nothing with hindering terrain, though. Instead, it simply says "Can this character use Stealth? Yes? Well, then lines of fire drawn to it are blocked."

Only a handful of game effects that can't really be blocked by anything at all (like Cosmic Spider-Man's trait) would be able to circumvent this special power.