The Rules Cyclopedia never fails to reveal something new with subsequent readings. This time, I found the Wheel of Fortune on page 242, between Wheel of Floating and Wheel, Square.
The best part of the item description is this:
If desired, the wedges may be numbered from 1-20, 1-100, or some other conveniently determined number, and a chart may be made with more varied results.
That's right - customization is encouraged. The basic Wheel of Fortune provides 6 positive results and 6 negative results, so an equal amount of both types of results makes complete sense.
Looking at other BECMI and BX sources, we see that eating rock chips in B1 and drinking from a fountain in B5 both provide random effects (d20 and d8, respectively). What all three have in common are the number of ways to raise and lower various (or all) attribute scores. B1 and the RC both provide free treasure in the form of cash, gems, and even minor magic items, as well as take it away. It's worth noting that BECMI doesn't have a Deck of Many Things (at least the Rules Cyclopedia doesn't), but the DoMT is a similar item worth looting of ideas.
Using all these as potential sources, I have this as my draft expanded d20 Wheel of Fortune.
It features 10 positive and 10 negative results, with source in parentheses.
1 - Subtract 1 from each ability score (B5)
2 - Add 1 to each ability score (B5)
3 - Subtract 1 from Prime Requisite (RC)
4 - Add 1 to Prime Requisite (RC)
5 - Permanently lose 1d4+1 hit points (B5ish)
6 - Permanently gain 1d4+1 hit points (B5ish)
7 - Gems on person crumble to dust
8 - 3d10 gems appear in your mouth, stuffing your cheeks (Goonies).
9 - Jewelry on person turns into cheap costume jewelry worth nothing.
10 - 2d4 pieces of jewelry appear on your body.
11 - Coins on person turn to lead.
12 - Coins rain down from above! type 1d8 1-2 copper, 3-5 silver, 6-7 gold, 8 platinum; 1d4 thousand copper and silver, 1d4 hundred gold and platinum.
13 - The least valuable magical item carried by spinner disintegrates (RC).
14 - A random weapon carried by spinner gains an enchantment (B1ish).
15 - Cursed! Roll on the Cursed! subtable below (B1ish).
16 - Blessed! Roll on the Blessed! subtable below.
17 - All nonmagical items carried and worn disintegrate into dust (RCish).
18 - All nonmagical items carried and worn become the finest quality possible, to include changing materials and workmanship.
19 - Spinner dies. No saving throw. (RC)
20 - Grants a wish, and the spinner knows it and can use it whenever they like.
Cursed! (d8) Note that a Remove Curse spell will suppress the curses for a time, but a true cure is required to finally be rid of each curse; knowledge of the true cure comes with the curse.
1 - Lycanthropy - d8 1-3 Wererat, 4-6 Werewolf, 7- Weretiger, 8- Devil Swine.
2 - Slow Healing - magic only heals 1 hp per casting; normal healing takes twice as long.
3 - Berserker - when combat begins, won't stop until all around are down, allies included.
4 - Unlucky - rolls disadvantage on all rolls.
5 - Marked - Charisma effectively reduced to 5 for reaction rolls, loyalty checks, and such.
6 - Hunted - something wants you dead - and it's coming. DM choice of monster.
7 - Polymorph - d6 1-4 become a talking normal sized animal; 5-6 become a monster. DM choice.
8 - Geased! - DM choice of what the spinner MUST do.
Blessed!
1 - Polyglot - gains the ability to speak and understand (but not read) 1d6+1 additional languages.
2 - Sniffer - can smell metal with concentration, as per the detect metal ability (like a magic sword). Full disclosure, I lifted this entry from the Idalium Story Hour on Dragonsfoot.
3 - Healer - can lay on hands to heal a person of disease, blindness, poison, or damage. 1/day
4 - Confident - Charisma raises to 18 for reaction rolls, loyalty checks, and such.
5 - Caster - can cast one useful spell per day: d6 1-3 Detect Magic, 4-5 Continual Light, 6 Knock
6 - Nature's Friend - animals are friendly towards you; you can Speak with Animals at will.
7 - Lucky - roll all nonattack and nondamage rolls at advantage.
8 - Regenerate - as per ring; note that weapons that damage regenerators affect you, now
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It occurs to me that a group of enterprising (and morally questionable) individuals, be they PCs or organized bandits, might force captives to spin the wheel to harvest the treasure they may generate.
After all, the rules themselves state:
A charmed creature cannot move the wheel, and each user can spin the wheel only once per day. p241
So anyone charmed cannot spin the Wheel of Fortune. Everyone else, though, can.
Forcing captives at swordpoint to spin the Wheel results in wealth-farming. Yes, the captives may die, but I don't see that being an issue to bandits (or many PCs). Why, an enterprising sort may even charge others for a spin, while a scholarly sort might try and document likely effects to 'find the pattern'. Canny individuals will eventually realize the bad spins that disintegrate wealth and items only affects items carried, so stripping naked (or to a loincloth for PG-rated games) mitigates those rolls.
If only using the book version of the Wheel of Fortune, there are 4 (out of 12) chances to score wealth: 1,000 gp OR 10 garnets OR a brooch OR a miscellaneous magic item. These treasures just appear. Me being me, I'd argue that this treasure comes from somewhere, likely a nearby dragon hoard or the treasure vaults of someone or something powerful. As written though, they just materialize through the power of magic.
Those wanting to cheat the house through telekinesis, other magic, or outright damage to the Wheel find that it all fizzles. All magic fails except for Wish - wishes involving the Wheel of Fortune in any way cause it to disappear, but for good or just teleporting away to another location, the rulebook doesn't say.
The rules do specify that the wheel weighs 20,000 coins (2,000 pounds) and can only be moved by a creature with 26+ HD or levels, meaning that only the most powerful PCs are going to be able to move this into their strongholds, and then only by brute force, as the wheel is immune to pretty much all magic. A mean translation suggests that even draft animals won't help, as they lack the HD.
It would be far simpler for PCs to turn the location of the Wheel of Fortune into their stronghold; it would likely be cheaper, as well.
A Cursed! but Wealthy regular spinner of the Wheel of Fortune
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A bonus entry I am not sure where to put:
Dragon - a rift opens above you, streaming down thousands of silver, gold, and platinum coins, as well as dozens of gems and pieces of jewelry. With this wealth falls 2d4+1 magic items. You dream at night of flight and flame, and find yourself changing ... shifting ... into a red dragon in 1d8 days. The DM takes control of this now-NPC.