No marshmallow, no custards, no cinnamon. Others can give a better explanation...
Some cinnamons aren't safe and some are an irritant. Ahlusion doesn't use them but a long time ago someone posted they may include cinnamon if you ask but I don't know if that is accurate.
Custard, buttery and ice cream flavors can not be made without the use of diacetyl nor their substitutes, acetyl propionyl or acetoin, which can morph into diacetyl. Diacetyl causes popcorn lung. There doesn't seem to be any authoritative information about what crosses the line in what amounts of diacetyl or its substitutes might be safe versus dangerous in e-liquid. Ahlusion does not use flavors that contain these chemicals irrespective of their popularity in the vaping community.
Wlad's long experience in the flavoring industry prior to making e-liquids means he has the expertise to know how to reliably avoid these chemicals. Dr. Farsalinos did a recent study where he found that 69% of the juices he tested contained diacetyl although some of the vendors selling those juices claimed they were diacetyl free.
Some marshmallow flavors contain diacetyl but some appear not to. One would have to ask Ahlusion why they don't include marshmallow notes in any of their juices.
I'm supposed to cut out nicotine for two weeks in advance of a surgical procedure, and let's just say that I'm having trouble with that. As a flavor-impaired ex-smoker, I normally get limited taste. Lack of throat hit with the zero is making this attempt frustrating...
High PG enhances throat hit. If you can't tolerate high PG or if it isn't getting the job done you might want to add a very small amount of Everclear or very high proof liquor to see if that helps. Some people who DIY use that method to enhance throat hit for their low or zero mg. juices.
Best of luck with your surgery. Hoping it is successful and that you have a very speedy recovery.
There is nothing like an Ahlusion sale to reduce any steel in my spine to a pathetic puddle.