Nullifier Crewman

The Nullifier Crewman is a Sniper Crewman that carries an energy field generator on his back. The spherical field not only prevents projectiles from entering (similar to Snow Globe), but it also dispels any present buffs as soon as players enter it. Firing at the globe causes it to gradually shrink and eventually dissipate the globe altogether, although it will regenerate after a brief period.

Tactics

 * Due to the Nullifier field having Object health property which does not accept Critical Hit damage, weapons that heavily depend on crits such as Soma or Amprex perform poorly against it.
 * Splash damage from explosive weapons and powers originating outside the field are nullified, dealing no damage to anything inside.
 * The energy sphere will remove any buffs active on Warframes caught inside it, and will render the Nullifier immune to direct targeting by all Warframe powers, including AoE and indirect powers.
 * Despite being a Sniper Crewman, the Nullifier Crewmen's behavior is a bit different; they will not attempt to bash enemies who get too close, and much like Arctic Eximus they will not attempt to take cover or run away. Nearby allies will also head inside the Nullifier Crewman's sphere, making it harder to kill them.
 * Nullifier fields absorb hitscan projectiles and deflect physical projectiles. Care should be taken when firing heavy weapons such as the Penta  and Ogris directly at a Nullifier, as the grenades and missiles may be reflected straight back to their source.
 * Certain ability projectiles (e.g. the Shuriken projectiles) can home in on the Nullifier, but if the shield is present then they will bounce off of it like normal projectiles.
 * Due to the Nullifier field's damage mechanic, low damage but high fire rate weapons like the Gorgon or Viper are most effective at whittling down Nullifier fields quickly.

Trivia

 * Nullifier Crewmen seem to have the same drop table as Sniper Crewmen.
 * Additionally, Nullifier Crewmen seem to wear the same suit that Sgt. Nef Anyo wears, albeit with yellow chest straps rather than white ones.
 * Oddly, the Codex image of Nullifier Crewmen seems to represent a standard Crewman with a black uniform and a jetpack used by the three Ranger variants in Archwing missions, whilst the in-game model has an additional helmet extension and a unique "core" pack on its back.
 * When summoned from Nekros, their shields will be the caster's energy color

Bugs

 * As of 15.5.7, occasionally, entering the field may jam your abilities permanently if the Nullifier Crewman is killed before you can step out of the field. You can fix this by entering another Nullifier's field and exiting it before it dies.
 * Currently, the Nullifier's field resists both explosives and continuous weapons from players hosting the session.
 * The Codex Scanner can scan his sphere (provided it is up) for a successful scan. [Might be intended]