You'll get a Tasha coin for each successful, completed run - about eleven fights in total, I think. If you lose a fight, the session ends and you get nothing. If you're struggling, use the Druid for your main character and use his Nature's Fortress Party Skill on every fight - it'll quickly boost your dice into pretty insane bonuses. Pair with Anna, Adrian, and whoever strikes your fancy so all die types are covered, and go ham.