Style

Ultimate Archwizards is a lighthearted game for one 2-4 hour session. It's a little more group-storytelling than some RPG games, with players describing NPCs when they succeed and fail.

Tips

The default answer to everything is "YES". Never say no.
If players want to use a skill, say yes. Do the players want to distract the lake full of alligators with an elaborate juggling routine? Say yes and ask for details on the act and how the alligators react.
If the players want to use a mastery, say yes. They can effortlessly defeat obstacles and minions.
If the players want to use a power, say yes. They can effortlessly defeat obstacles and minions. They should either majorly damage or defeat the Overlord if they use a power. That said, encourage them to use up their Powers before the final battle if possible instead of saving them up.
When using skills, the players may be unsure how to describe success or failure. Some prompts to help them could be "Great, you succeed. Tell us how!" or "You succeed, but...?" or "It doesn't work, what happened instead?".
For complete failure, you CAN suggest a failure mode at first to get the players used to the idea, but get them used to taking control. An example prompt could be "Out of nowhere, Grandma walks in the way. Describe how that happened?". The idea is to get the players used to the idea that failures should be more interesting than the obvious "You missed."
When the players succeed or fail, try to keep pushing them to say more words until they've added interesting detail or a new twist. They are in charge of thinking of twists, not you.
Get them used to the improv flow, gradually streamlining prompts "You succeed, tell us how?" to "Success, you shoot him. And?" to "You shoot him, and?"

Mastery

Each player has mastery over their Archwizard school. This looks similar for all players.

Sample laser mastery: Laser Magic. You can freely use any kind of laser magic, at any time. You have unlimited mana. Your lasers come in all colors and always have perfect aim.
Sample genie mastery: Genie powers. You can float around as smoke or solid, go inside any lamp or ring, etc.
Sample pro wrestling mastery: Ultimate wrestler. In addition to your cool costume and soap opera backstory, you're also the best wrestler in the world. Any time you are in physical combat, you win.

Powers

Powers should be really powerful! They can be one time use, or have unlimited uses. With a game this short, there's not really much difference. Each player gets 2 special powers (initially sealed). Powers never instantly defeat the Dark Lord.

Sample laser power: Hyper Beam, one use. You summon a massive laser, which destroys everything in its path (up to moon sized). One use only.
Sample genie power: Grant any wish, unlimited uses. Keep track of how many wishes you have already granted. You gain a special skill only you have, "Grant wish (+0)". Whenever you grant a wish, roll a skill check against a difficulty of the number wishes you have already granted. On full success, the wish works as expected. On full failure, the wish has ironic bad consequences. A wish can't directly defeat the Dark Lord.
Sample pro wrestling power: Finishing Move Combo, unlimited use. Whenever you defeat an enemy in physical combat, you can use their unconscious body as a weapon against another enemy, defeating the second enemy instantly.

Seals

The players start out with their powers sealed. They still have mastery, but they can't use their special powers. The first time any player fails a challenge, their powers unseal in a cool cutscene or monologue they narrate, describing how they actually succeed. The other players can now release their seals at any time.

Difficulty

The system is designed to run in one session. Ramp the challenge difficulty up from 3 to 6 over a single session. The very final challenge during the fight with the Dark Lord can even be difficulty 8. The challenge level should be the number to beat with skill rolls (+1 or -1 based on whether it sounds like it would work), but also a general gauge of difficulty. Remember, the players are Ultimate Archwizards, so even the low-level minions at the start should be able to level cities.

Challenges should be designed around the characters and skill list. The point of challenges is to let players look cool beating them.

2: (Too easy!) The PCs have to find a good outfit at the mall, while a gang of hoodlums chases them.
3: The PCs are trapped in a hypnotic dream, and can only escape by realizing they're dreaming.
4: The Dark Lord's castle is impenetrable, except for one small weakness, protected by alligators.
5: A small army with tanks and rocket launchers assults the PCs.
6: The PCs must reach the Dark Lord's castle. The castle is in space, but Earth has not yet invented the combustion engine.
7: The Dark Lord's trusted lieutenant, a suave and handsome talking magical lion, tries to seduce the PCs. Each time he fails, he resets their memories with his time powers and tries again.
8: The Dark Lord has thrown the moon directly at one of the PCs, and it is seconds from hitting them.
- Punching the moon in half might only need a roll of 7--it's very plausible.
- Dodging the moon might need a roll of 8--doable, makes sense
- Charming the moon the turn around and fight the Dark Lord, by singing an epic ballad about the party's friendship for each other, might need a roll of 9--moons don't usually do that

The Dark Lord

The Dark Lord is incredibly powerful--they have absorbed the power of many Archwizards in previous solar systems. They may optionally have one or two obvious weaknesses (HAHA I AM INVINCIBLE... as long as they don't notice my missing knee armor... and my irrestistable love of kittens...). If it ever looks like the Dark Lord might be defeated too early, just pile on even more powers. If the players blow up the entire orbiting Dark Fortress before meeting the Dark Lord, the Dark Lord should just shrug it off.

The Dark Lord should not appear, or appear only to taunt the players, until the end of the session. The Dark Lord is defeated at the end of the session. The Dark Lord definitely should never win, that's lame.

In the final battle with the Dark Lord, if the Dark Lord ever looks like they might defeat the PCs and the situation is hopeless, the PCs assume their TRUE ULTIMATE FORM in elaborate cutscenes, gaining unlimited mega superpowers. On the other hand, if it looks like the PCs have it the situation totally handled, the PCs assume their TRUE ULTIMATE FORM in elaborate cutscenes anyway, and really just toss the Dark Lord around.