It seems that Aventurian priests in general get a secular training on par with laymen. The most flexible approach should be clerical lenses, which can be combined with a suitable occupational template (e.g. lawyer or scribe for a cleric of Praios; healer for Peraine; thief, merchant or con-man for Phex). We can add a monk occupational template, for those dedicated to monastic lifestyle (although there are far less monasteries in Aventuria than in the European middle-ages).
Clerical lenses should certainly contain the Blessed (Heroic Feats) advantage. Patron (Deity) is also suitable for priests of the Twelve Gods pantheon plus the higher ranks of associated demigods.
From there on, add either Clerical Investment (use limited to slowly repleneshing Energy Reserve, as magic use) for TDE4-style "divine casters" or supernatural advantages (Blessed, Intuition, Resistance (Supernatural Powers), Telesend (limited to other priests)) for "old-school" TDE-priests (both with a power-modifier "Divine", -??%).
This Wiki handles the conversion rules for the The Dark Eye setting.
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