The description of the artificer's homunculus servant states:
In combat, the homunculus shares your initiative count, but it takes its turn immediately after yours. It can move and use its reaction on its own, but the only action it takes on its turn is the Dodge action, unless you take a bonus action on your turn to command it to take the action in its stat block or the Dash, Disengage, Help, Hide, or Search action.
The homunculus has a limited number of action options in combat, and most require the artificer to use their bonus action on their own turn. This (closed) question lists the reactions that are generally available in the game, but the homunculus can't have feats, use the Ready action, or take an Opportunity Attack.
Yet the rules specifically go out of their way to mention that the homunculus can "use its reaction on its own".
Question: what reactions can it use?