What little testing I've done seems to make it seem like stymie basically takes full resists and turns them into half resists. But only on mobs that don't give you the completely immune message. Kinda neet I guess if you want to sleep a skeleton for 45 seconds without waiting for an immunobreak but overall very lackluster. This is something I would've expected as a normal ja with a 5-10 minute timer gotten while we leveled up not a new "2hr"