The infinitive form of the verb is: tēmagon
v. to prick, to poke
Rōvon dēmalion rōvi jenti tēmas. — A great throne pokes a great leader.
From Dothraki Wiki: https://wiki.dothraki.org/High_Valyrian_Vocabulary
Firstly, I know this part of the course is for learning some noun forms, but I try to show the link for Verb Tables from the Wiki in some exercises. I hope to find more information about this verb and more example sentences or exercises. Here, the Wiki is showing the translations and IPA pronunciation.
The ending -agon is the same used for A-stem verbs, but it can be also for Consonant-final verbs. For example, the verb gaomagon ['gaɔ̯magon] (to do) is a Consonant-final verb, and I am guessing if the verb tēmagon is in the same class or A-stems. A very simple difference for Vowel-final verbs: The first person plural is a long -ī.