
The King of Something |

In my game I have a witch who loves to cast Aboleth's Lung as a forced suffocation for easy kills. He argues that since it makes it so you can only breathe water and your lungs are filled with air, which isn't water, he argues that you immediately start suffocating and don't get the chance to hold your breath as you can't breathe the stuff in your lungs. Is this how it is supposed to work? I'd rather avoid having to piss him off by making him face constructs and undead more often than not because I'd rather not have a session filled with make a save or die.
I know how suffocation rules work, and he's insistent that this is how it should be ruled.

Quixote |

I'd have to point out that, if you tried to cast this on an ally and his interpretation was true, they would also immediately start drowning. Unless...they somehow deliberately started drowning (on water) before the spell was cast? It's all rather counter-intuitive.
As for putting a stop to it, his argument makes sense, but try offering a counter: it's a lvl2 spell. No lvl2 spell should directly result in an enemy's death after nothing more than a failed save. Ask him to be reasonable and fair to everyone at the table. If he will not, then ban the spell. Or him.

The King of Something |

I'd have to point out that, if you tried to cast this on an ally and his interpretation was true, they would also immediately start drowning. Unless...they somehow deliberately started drowning (on water) before the spell was cast? It's all rather counter-intuitive.
As for putting a stop to it, his argument makes sense, but try offering a counter: it's a lvl2 spell. No lvl2 spell should directly result in an enemy's death after nothing more than a failed save. Ask him to be reasonable and fair to everyone at the table. If he will not, then ban the spell. Or him.
That is a good point you make on how your ally would immediately start drowning. I'll try reasoning with him using this information.
EDIT/UPDATE: I'm in an awkward place where I sort of live with this individual and we're not related, and so banning him is very much off the table. We're good friends but I'm trying to avoid an argument that would result in him getting upset, but so far reason isn't working. He doesn't care that it's a level 2 spell, and that it should work as written. The problem with how it's written is that it is ambiguous.

The King of Something |

Is the player playing a Gillman? (Asking because Aboleth's Lung is only supposed to be available to Gillmen.)
If not, I'm surprised you'd allow the spell in the game.
I don't see where you have to be a gillman in the spell, where is that ruling at? It said it was in the witch spell list so I allowed it.

Dasrak |

I don't see where you have to be a gillman in the spell, where is that ruling at? It said it was in the witch spell list so I allowed it.
Says so in the subsection in which it appears
The following options are available to gillmen. At the GM's discretion, other appropriate races may make use of these as well.

PFRPGrognard |

That is how it is written in the book, but you are THEE GM. You don't need a second edition Core Rule Book to tell you that you are in charge of the game and can adjust it as needed. For cheesy stuff like this, you can let it work a few times and when you've had enough, tell the player that it is limited to willing targets.

Quixote |

...and so banning him is very much off the table. We're good friends but I'm trying to avoid an argument that would result in him getting upset, but so far reason isn't working. He doesn't care that it's a level 2 spell, and that it should work as written. The problem with how it's written is that it is ambiguous.
I was just making an observation that sorta'-kinda' supports common sense; I don't think it's a very strong argument itself.
I think "this is my game and I am outlawing/changing the spell because it'll help how the game plays out" is a much stronger argument.Of course "this spell isn't available to your character" is also a strong argument, and probably one he'll have to respect, but the second one is all you need.