Personally, I feel it is fine as it is. If we think about how Wizard works, it's a mega direct damage trick, but it also doesn't deal its own damage, like Explosion. At that, I believe the issue is cards like Jack-O-Lantern dealing too much damage as a single card too quickly, and Redemption allowing significant damage over time, as well as more than doubling the normal potential of Explosion with use of S draw and cards like Wrath of Marcos.
Basically, I'm pointing the finger at cards that are more obviously broken in general use, before affirming that cards that have a more specified use are broken in that use. Changing these first could cause them to be underpowered when the card that is the actual problem is changed later.
Remember to aim high. But also remember, you must aim for the next step, or you will never reach the top where your ultimate goal awaits.