I think Lone Wolf is pitched as a narrative game, so hopefully newbie GMs aren't going ot be investiging all their stock on running combat after combat. Lone Wolf itself is a mix of combats and story, and many of the big epic fights had ways to one-shot the villan (Barraka and the holy water, Kimah and the dagger of Vashna, Gnaag and thre Sommerswerd).
I guess for advice, balancing Lightning Hand is as has been mentioned
- make WP count. I had an evil player wizard with lightning hand blast quite a few NPCs dead and come <-> close to one-shot killing a player with a lightning bolt. It was a short game, and yet he was scrambling for WP by the end. Lightning Hand is a very costly power balanced by being useful. Even for a character with no cares other than survival! A good player also has to defend allies and NPCs and complete a mission!
- let people have their moment, definitely. Being able to wipe out a legion of tough opponents give the game the epic Lone Wolf feel. And cements the reputation of a wizard in a fantasy realm. If that victory leads to the wizard having a reputation and so the group facing a tougher fight next time, it's a consequence that still sends the nice message of 'you guys are so powerful the enemy is really afraid of you!'
- don't let your main villain be in the position to be one shotted. By the time he's front and centre, he should not be the main challenge. Great if he can be, but also great if he's there because he has no other choice, and if therefore the players get to blast him in one shot, it's their reward. Lone Wolf had Barraka destroyable by holy water, Kimah killable with a thrown Dagger of Vashna, and Zagarna/Gnaag blasted to heck by the Sommerswerd. And Vonotar was instantly captured without a player-required fight in Kalte once his beasty was dead. The big bad is allowed to keep out of the way of a known poowerful foe, weakening them from afar. And is allowed to be in a world of hurt and at the mercy of the group if he has to put his head up.