[Autumn]

being airborne disables KB immunity across the board afaik, and bellowing stag's knockback is airborne conditional so it'll always ignore it.

You'd think this would be the case but in some cases it is not, it is sadly just something that is a per skill basis, a little known knockback that works regardless of an airborne opponent or not is Sharenzan.

Typhur for instance doesn't ignore knockback immunity on airborne targets, despite following the same logic as many others.