The Collaborative International Dictionary of English v.0.48:

Purgatorial \Pur`ga*to"ri*al\, Purgatorian \Pur`ga*to"ri*an\, a.
   Of or pertaining to purgatory; expiatory.
   [1913 Webster]

WordNet (r) 3.0 (2006):

purgatorial
    adj 1: serving to purge or rid of sin; "purgatorial rites" [syn:
           purgatorial, purging, purifying]
    2: of or resembling purgatory; "purgatorial fires"

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "purgatorial":
   Acherontic, Lethean, Plutonian, Plutonic, Stygian, Tartarean,
   apologetic, ascetic, atoning, chthonian, chthonic, cleansing,
   compensational, compensatory, devilish, expiatory, expurgatory,
   hellborn, hellish, infernal, lustral, lustrational, lustrative,
   pandemoniac, pandemonic, penitential, piacular, propitiatory,
   purgative, purifying, reclamatory, recompensing, redeeming,
   redemptive, redressing, reparative, reparatory, repentant,
   repenting, restitutional, restitutive, restitutory, righting,
   satisfactional, squaring, sulfurous