Was curious about the anti synergy myself, so I went to look at Thunderhead. From what I can understand it'll summon the sparks after Beakered Lightning already did the damage since the wording of Thunderhead says "After you play a card with overload".
This is really good in even shaman I think. You can run an overload package that might be really strong. On turn four you play thunderhead plus this and you can wipe a pally board before they get a chance to level up, even get through divine shields and rush minions kill those. This won't kill any of your own minions unless they're already damaged.
It's playable without thunderhead and will occasionally get a boost from spell damage totem.
There is also Zap to play with thunderhead. It really weakens the overload penalty because you're getting 1/1s for that mana.