Here's why:
* Verb: The base form of the word is "summon", meaning to call upon or request the presence of someone or something.
* Past Participle: Past participles are used in different grammatical structures:
* Perfect tenses: "The knight had summoned his troops."
* Passive voice: "The troops were summoned by the knight."
* Adjective: "The summoned guests arrived late."
So, while "summoned" can act as a verb in some cases, it is primarily a past participle.