So, a player in my campaign, a sorcerer, has a background of drinking problems and joked about having a spell in which he can summon beer.

I've toyed around with the thought of allowing this, but as a 1st level spell and it transmutes liquid into beer for a short time.

https://www.dndbeyond.com/spells/599892-transmute-liquid-to-beer

I was thinking, if he was to use it on water, sure, he'd have a momentary buzz but once it goes back to the water he is fine. But if his character was, brave enough to convert slimy water or poison or something toxic to beer, then once reverted back, he'd suffer the effects of the previous state.

I've also put in a beer alcohol strength check, so if it's strong, then it'll hinder him in some way.

Any suggestions on how it could be improved/balanced?

Should not work on poisons. That can cause problems for when the beer reverts to a poison two hours after they drink it.

I'd just have it that it works on potable water only. I'd extend the effect to allow it to also make wine. I'd remove the 1d10 strength thing. I'd just say they can transform the water into any beer or wine they have tasted before. I would say it can transform up to 2 cubic feet of water. I'd say the whole volume would need to be within 5 ft but it does not need to be a jug you are holding (what if they didn't have a jug and were just using the barrel etc). I'd have it be permanent - Instantaneous - rather than a duration. If you're concerned about using this for a business or something then I'd instead say only the beer or wine that was not consumed will turn back. Keeps it simpler.

I'd avoid mentioning poisons or such as. Technically alcohol is a poison. We feel drunk because it's destroying cells in our system. The word "potable" covers all you need for ensuring they can't turn nasty or toxic liquids into beer or wine (potable means "safe to drink").

Personally, if it's temporary and only affects like a few mugs at best, I'd make it a cantrip and just add if they cast it again any previously transmuted liquid that has not been consumed will instantly revert back. All the free alcohol they want for a small group but not enough to make a business of it or profit in any reasonable way. Given that getting drunk is a detriment (commonly just being the poisoned condition). I mean, beer is a few copper, the whole party could get rat-arsed drunk on a single gold coin if they wanted and most campaign worlds have lots of places to get beer. So it wouldn't be OP or gamebreaking.

Hope this helps.

Quote from Cyb3rM1nd >>

I'd avoid mentioning poisons or such as. Technically alcohol is a poison. We feel drunk because it's destroying cells in our system. The word "potable" covers all you need for ensuring they can't turn nasty or toxic liquids into beer or wine (potable means "safe to drink").

 

 One would think, but damage effects that have a potential for a negative number specify (minimum 0) so that munchkins don’t try to claim that “negative damage = healing.” 🙄