A 100 speed wild cat was transformed into a writhing mass of primal chaos by a corruption trap. According to both blessed stethoscope and monster memory, the writhing mass is also 100 speed. When moving away from it with a 100 speed character, it is usually able to follow and attack. When waiting next to it, it often gets two rounds of attacks. Spending a turn outside the level seems to fix the issue. Save file attached.