I am playing a level 19 Fiend Warlock in a campaign, and the wizard has wish. Would wishing for each of the 4 party members to gain two levels in any class they choose be under the extent of wish? The spell states "The GM has great latitude in ruling what occurs in such an instance; the greater the wish, the greater the likelihood that something goes wrong. This spell might simply fail, the effect you desire might only be partly achieved, or you might suffer some unforeseen consequence as a result of how you worded the wish." This implies that this could be done, but with great consequences. Edit: The DM has told me that this wish would not work.
It depends highly on your game. This would be a good topic to discuss with your DM.
Read the spell, carefully
You might want to read the wish spell carefully. You'll note there are essentially three uses of the spell:
- Duplicate any spell of 8th level or lower
- Create one of the effects listed
- Achieve something beyond the listed effects
After the list of effects, wish says:
You might be able to achieve something beyond the scope of the above examples. State your wish to the GM as precisely as possible. The GM has great latitude in ruling what occurs in such an instance; the greater the wish, the greater the likelihood that something goes wrong. This spell might simply fail, the effect you desire might only be partly achieved, or you might suffer some unforeseen consequence as a result of how you worded the wish.
It then goes on to give some examples of unforeseen consequences.
Your proposed wish goes way beyond what's in the spell description
What you propose is vastly "beyond the scope" of the examples in the spell. Vastly.
You mention giving party members each two class levels. However you calculate it, that is significantly more powerful than the examples listed in the spell. I won't even mention that the rules end leveling at 20th . . . and 19th plus 2 levels is 21st.
Casting wish can be stressful
I will also draw your attention to the last paragraph of the spell:
The stress of casting this spell to produce any effect other than duplicating another spell weakens you....
You will take damage every time you cast a spell
After enduring that stress, each time you cast a spell until you finish a long rest, you take 1d10 necrotic damage per level of that spell. This damage can't be reduced or prevented in any way.
You might never cast wish again
Finally, there is a 33 percent chance that you are unable to cast wish ever again if you suffer this stress.
What would a reasonable DM do?
A reasonable DM might take you aside, and explain how over-the-top your request is, and suggest you re-think it, in line with the spell as written.
Or, a reasonable DM may well choose to grant such a wish only partly, as the spell suggests, whatever that means.
Or, a reasonable DM might just look at you and say, "Are you sure? Are you really sure? You've read the spell, right?" And if you go ahead, tell you to switch to your backup character, because this one is no longer playable, having turned itself into a magic item belonging to your patron.
Or, a reasonable DM might have the cosmic police (in whatever form appropriate), show up and slap your hand, essentially causing the spell to fail.
What a reasonable DM is unlikely to do, very unlikely to do, is give you what you're asking. It's so unbalanced that it effectively makes the game unplayable. I mean, if that's today's wish, what's tomorrow's? Why not wish for unlimited power? Or your enemy's skin as a throw-rug? Or to just "win"?
But what a reasonable DM would do matters much less than what your DM would do. After all, Games are different one table to another though. Some games are very high-magic and highly customized. Some games are gritty and low-magic. What is reasonable at one table may not be reasonable at another.
After all, some games are gonzo, and over-the-top. I've played in a campaign where by level 20 we were dripping in artifacts (with additional "legendary" attunement slots, even) and fighting god-like entities. (Although, even in that game, as over-the-top as it was, the wish you describe would have been foolish beyond belief, and world-striding wizards would have quaked at casting a tenth of it. But, you know, games vary.)
Should you try this?
You ask, "Do you think I should try this?" That's hard for us to answer. This site is specifically not a discussion site, and everyone will have a different opinion.
So I invite you to ask yourself your own question, first noting:
- What you ask is vastly beyond the scope of the spell, as described in the spell's own text.
- The spell itself suggests such beyond-scope uses may well cause a result "effectively removing you from the game".
- There's a 1/3 chance you'll never cast wish again, and you'll be temporarily severely weakened.
So what do you think?
Ask in game
Given the possible consequences of a wish going awry, you might want to do some research. In game, you may wish to consult with the arcane glitterati as to the effects of wish. It is a common trope that there are magical libraries or universities where such things are recorded, so perhaps it exists in your game.
Talk to your DM
Finally, and most importantly, talk to your DM. What is most important is what happens in your game, and the DM is the best person to give you insight on that.