Entity-specific Damage Invulnerability

Damage type invulnerability for an entity can be set with the following command:

/dmginvuln |entities| set |damage_type| |invulnerable|

/dmginvuln @a set fall true - sets fall damage immunity for all players

You can query damage type invulnerability with:

/dmginvuln |entities| get |damage_type|

/dmginvuln @e[type=creeper,limit=1, sort=nearest] get onFire - gets whether the closest creeper is invulnerable to fire or not