Another note to add to the usefulness of medusa is to load her up with starting energy. Then, pair her with dungeon man and shaman when attacking a line without dark horse, bone or void. Once she gets into position she will instantly freeze the enemy team. After they are frozen you have a few seconds to start destroying their line.
Another hero to worry about is plant. She has a very high amount of tenacity and seems as though she is out of the stone and ready to defend drac or archer, the worst toons to let go.
As far as Alex's post about buffing freeze or stun:
Spirit wolf's legendary increases the duration of disabling skills.