Back in ladder reset 2, after the synergy patch I made a HC ladder lightning sorc. I got to lvl 45 and died from a trapped waypoint (about a week's worth of work gone...) I never used nova, but it seemed too weak. So here is my tale and advice.
Anyways one thing to remember about lightning, not CL, is it will go through all monsters (in a fat line). So if there are 8 monsters more of less in a line (its one
fat bolt of lightning, they can be far apart) it'll strike them all for the 1-x dmg. I went 2/3 lightning, lightning. The dmg does get to be crazy because the mastery is 50% and then +12%/lvl (vs fire of like 30% + 7% or something, stats off the top of my head). Then later on in the game after you reach lvl 20 of lightning it will grow exponentially (8%) based on the 3 synergies it will take. Of course fire and ice have their great bonuses and will grow similarly. One thing about lightning sorc, because the spells take a bit longer to cast, +casting speed is much more effective. Frames reduce from 16->14 with 10% faster.
Personally, I was deeply disappointed with CL; it will ricochet off an enemy and hit another up to the number of targets. Unless you get it up to about lvl 40 or so, it is almost better to let the lightning just arc through the enemies in a straight line apposed to bouncing off one enemy (or not at all if there is only 1 enemy, and it didn't do tag backs. It will go in a triangle shape if there are 3 enemies though). By lvl 20 it will only bounce 9 times, so best case scenario is there is a triangle of enemies and each gets hit 3 times. Another thing I hate about CL is when it targets an enemy far away apposed to a close one, the enemy often can move out of the way before the lightning gets there (funny... last time I checked, lightning was faster than me) and will go off into the distance and you just wasted about 2x mana apposed to a regular bolt.
I don't know if it is normal to reach lvl 45 on HC ladder in about a week, but I liked the way that lightning went through rows and rows of enemies, slaying a huge number (in act 3 I could kill close to 8 fetishes per cast of regular lightning). I even had more life than mana (du'h its HC), so my killing speed should have been reduced drastically compared to a softcore character. I'd drink mana potions like a monkey (base skill lvl 8 warmth). Well thats my story. The best thing to remember with lightning is to play to use strategy (like Hydra sorc, or WCIII).
For HC players out there, Durial is best fought in a group with someone above lvl 40(well du'h), letting you move forward to slay Meph by yourself or similary. I had a slight disadvantage, not having a higher lvl character to drop items into my sorc because I stopped playing D2 a while ago, but am playing with the idea of playing it again. I had about 80% resist lightning (meph and diablo were do-able) and 90% (97.5% after short duration) resist poison (Durial on NM wasn't too hard) made the bosses much easier.
Below is a great site for pre planning characters, it almost 100% right, I dislike the people who run the site, but the character planner is good.
http://www.d2items.com/skills.php