So a bit more feedback now that I have all his upgrades unlocked.
When you and another wizard both attempt to jump on each other's heads as @asabaida and I found out a couple times earlier today, you both fail but the cooldown is reset so you don't lose it.
With a wizard on your head, your legendary hat won't play it's animation or sounds when you vanquish players/bosses/champions/heroes.
Two Headed Dragon let's you hang around on someone's head for a very long time in Ops as each vanquish restores a chunk of your co-star meter. It's very handy as co-star has a high rate of fire and all the other benefits so you can stay up there for a prolonged period. It has a lot of potential use in PvP modes too, but it heavily depends on how many targets you and your host vanquish, it's much easier to vanquish a ton of enemies in Ops.
Blinders off is my favorite upgrade as it increases the arc for Starz Align from about 90 degrees to 180 degrees. This is extremely handy as it means it's easier to coordinate the bonuses associated with the buff.
Dust and Echoes looks to be very powerful in certain game modes; especially Team Vanquish, Vanquish Confirmed, and Battle Arena. It's pointless in PvE, but could be a good use one of your wizard build slots to have it in those modes. It does require you to vanquish enemies with spell disaster to trigger (making enemies unrevivable), and costs 4 but with good timing and especially against lower health plants, it's handy.
You and your host can get a lot of xp from the starz align xp bonuses you both get for assisting and vanquishing with each other.
Zee-lixir can be a lifesaver for yourself and your team but aiming and timing are crucial. I've saved people from chili bean bombs but also failed to time it for a super sap trap that detonated too quickly and almost got one-shotted by it. It will take practice to use it well. If you're in Chomper's goop you can't use it to mitigate the effect since it is also turned off but once out it can help. I used bottle bouncer with it briefly but it's hard to predict the extra bounce destinations.
I feel that Wizard has some of the most appealing upgrades and with 7 slots we're forced to make hard choices on what we want for the 3 currently available builds. This is the first character where I wanted to use so many upgrades together so much. This is good game design as you should be forced to make choices in a game that matter to how you play. He's one of my favorite characters in BfN.