Yeah, I ended up having the tutorial being hella rushed. The same fire affect you used to light the portal is also what you use to damage the boss. When the drawing is recognized, fire is spawned at your mouse curser so you spawn fire on the boss to damage it. Also thank you :)
Very nice! The progression of difficulty as well as the progressive introduction of powerups feels very fluid and I definitely had to scratch my head a few times so I think there's a nice amount of difficulty to it as well.