I agree, a scholar for instance is pretty impossible to kill even with three people whacking it at the same time. Simply because Eos can keep him alive by himself, outside of all the spells the scholar casts himself. This even more so when he's running or using sprint.

White Mage is a little less indestructable, but still.

How about... if you're running and get hit in the back, you get stuck with this Movement Speed debuff just like all the monsters give you. Monsters do it, why not we? Would stop people from running around endlessly while not changing very much to the actual game/fighting.