Learn German: Gestern sprach ich als mutiger Zwerg mit der Wache. - Yesterday I spoke with the guard as a brave dwarf.

The particle als (meaning 'as' or 'in the role of') makes the following noun match the case of the person or thing it refers to. Here, als mutiger Zwerg refers to the subject ich, which is in the nominative case.

Why does the adjective mutiger end in -er?

Because there is no article (like ein or der) before it, the adjective has to do the heavy lifting to show the gender and case. Since Zwerg is a masculine noun in the nominative case, the adjective takes the strong ending -er.

Is sprach the Präteritum (simple past) form?

Yes, sprach is the Präteritum form of sprechen (to speak) for ich. While spoken German often uses the Perfekt (like habe gesprochen), the Präteritum is very common in written storytelling or fantasy roleplay, which fits the context of this sentence perfectly.

Wait, Wache is a feminine noun (die Wache). Why does it say der Wache?

The preposition mit always requires the dative case. In the dative case, the feminine article die changes to der, which is why it becomes mit der Wache.