Killing Medusa is easy on Trickster. Getting her head is not.
Best strat is luring Medusa to the entance, positioning in front and using the pawn command sequence: 1-"Wait!", 2-"To Me!", 3-"Help!" to reset AI and trigger skill.
Kindhearted Thief Pawn has only Formless Feint and Skullsplitter. Do not use Aromatic Rally as it locks out pawn commands. Dragon's Delusion has no effect, I was using it for pawn behavior.
It should be doable in 30 sec, since Medusa usually opens with petrifying glare.