The discipline level used to recruit it decides which version it is (inferior or superior). This does not change once it is in play.
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Masquer
Wraith with 1 life.
Masquer is immune to non-aggravated damage. The employer gets +1 intercept. You can burn this retainer to give any minion +1 intercept.
As above, but Masquer has 2 life.
Rulings
Immune means damage is not inflicted, even if non-preventable or outside combat.