Well I would wager that it would be immune. The sight doesnt have any specific source for this however, but they are pretty reliable.

They were confirmed on Tuesday when the Nightfall unexpectedly popped up, and the mobile app showed a list of new modifiers.
I'm not sure if they're ALL of the new modifiers, but it'd be neat if we could have more buffs to go along with the debuffs.

Found these on Destinytracker.com

:-(

I'm excited for these, and I really hope that the new Heroic Strike playlist just gives you random modifiers (maybe with increased difficulty the longer that you stay in matchmaking along with your increased rewards)

Match Game - Enemy shields are resistant to all unmatched Elemental Damage.

Resistant, or immune? Because they already 'resist' unmatched damage…

Chaff - Player radar is disabled.

Fresh Troops - Some enemy squads have been fortified with additional reinforcements.

Ironclad - More enemies have shields.

Match Game - Enemy shields are resistant to all unmatched Elemental Damage.

Found these on Destinytracker.com

Bloodthirsty could be a problem, especially if you are fighting Hobgoblins or Sniping Vandals.

Chaff - doesnt seem like it will be THAT big of a problem.

Fresh Troops- more bang bang

Iron Clad - longer bang bang

Match Game - Will be pretty interesting. This will force people to think about their selections beforehand.