if a head chef gives a head chef vampirism it should also apply leech

[stray dagger]

this would enable you to stack them, for the extra tankiness and healing

[stray dagger]

||"why are the chefs giving each other head?"||

[clear spruce]

Head Chefs aura is already buffing itself. And since you can't stack vampirism twice, putting one head chef next to another, does nothing.

[stray dagger]

Exactly. I believe it should do something. Like... Give the tier 1 version of the aura - leech. But only to other head chefs.

[dense obsidian]

Perhaps I'm misinterpreting what you're wanting but the aura does work alongside the aura already. Every fighter can get 50% lifesteal like this (or more if you can get the Vampire legion spell).