[raven had followed them as soon as he could, floating up at a moderate speed, landing behind them just in time to see jason stab one. he quickly takes his knife and pricks his finger, dripping blood onto the paper and focusing--not saying anything out loud, just concentrating and trying to feel for how the spell works.

the dust from the nearby imp dissipates, that much is obvious to all three of them]

... keep going.

[he says, shreds the paper, and takes out another sheet to repeat the process]