Desiring to turn young people away from those (wretches) who are called Chaldaeans...
Translation of the full text:
"Against astrologers. The philosopher Favorinus -- desiring to turn young people away from those (wretches) who are called Chaldaeans and who promise that they will tell from the movements of the stars everything that will happen -- (always) said that they were not to be approached or consulted in any way."
PHILOSOPHUS: "philosopher". Nominative case to show the subject of the indicative verb.
AVERTERE: "to turn away". Infinitive mood to complement VOLENS. The dictionary form is AVERTO, AVERTERE.
VOLENS: "wanting, desiring, wishing". Nominative participle modifying PHILOSOPHUS. The dictionary form is VOLO, VELLE.
ADULESCENTES: "young people". Accusative case to show the object of AVERTERE.
AB: "(away) from".
ISTIS: "those (wretches), those (nasty people)". Pronoun in ablative case, as required by AB, normally used with a disparaging or pejorative tone. The dictionary form is ISTE.
QUI: "who". Relative pronoun in the nominative case to show the subject of VOCANTUR and POLLICENTUR.
CHALDAEI: "Chaldaeans, Chaldeans". Nominative case to show the predicate of VOCANTUR.
VOCANTUR: "are called, are named". Plural verb, indicative mood, passive voice--the dictionary form is VOCO, VOCARE.
SE: "themselves, they". Accusative case to show the subject (!) of the infinitive verb DICTUROS ESSE.
EX: "out of, from".
STELLARUM: "of the stars". Genitive plural form--dictionary form is STELLA.
MOTIBUS: "movements, motions". Ablative plural, as required by EX. The dictionary form is MOTUS, MOTUS (a noun of the fourth declension).
OMNIA FUTURA: "all future things, all things that will be". Dictionary form of the adjective is OMNIS. Dictionary form of this participle (future tense, active voice) is actually SUM, ESSE.
DICTUROS ESSE: "will say". This combination is the future active infinitive of the verb DICO, DICERE. Such F.A.Infinitives are built with the future-tense active-voice participle, coupled with the infinitive ESSE.
POLLICENTUR: "they promise, they are promising". Plural verb, indicative mood, passive voice (though active in meaning, a situation termed "deponent")--the dictionary form is POLLICEOR, POLLICERI.
NULLO MODO: "in no way, not in any way". Ablative phrase used adverbially. Dictionary forms are NULLUS and MODUS.
EOS: "they, them". Accusative plural form of the pronoun IS, EA, ID, used as the subject (!) of the infinitive verbs ADEUNDOS ESSE and CONSULENDOS (ESSE).
ADENDOS (typo for ADEUNDOS) ESSE: "are to be approached, should be approached". This is an example of the gerundive (a.k.a. future "passive" participle) with ESSE to construct a future "passive" infinitive. The dictionary form is ADEO, ADIRE (a compound of the verb EO, IRE).
CONSULENDOS (ESSE): "(are) to be consulted, (should) be consulted". Dictionary form is CONSULO, CONSULERE.
DICEBAT: "was saying, (frequently) said, used to say". Imperfect tense, active voice of the verb DICO, DICERE.