[Well, the closest he knows of is a Hydreigon... so...]

A draconic beast, with many heads. Chop one off, and two grow in its place. Do you know that this game uses the same hydras you recognize...? If not, your thought is as unsupported as mine.

[A bit of a pause, as he considers what he saw before the mission properly started.]

Come to think of it, maybe it's not an actual hydra, but instead someone or something with hydra-like qualities.