As for me:
1)visible footsteps
2)panic - everytime an opponet(humans mostly) will be hit by a specific ability there will be a chance that he will start to panic, run around screaming and thus losing his fighting capabilities for a few turns
and most importantly:
3) additional reward for every backer(or every one that pledged enough to recieve the game) - an ability to change the appearance of currently worn armor and weapons into unique backer-only one. The pants and potion sound great but they look like something of one use only, whereas I think that backers would love to show off with awesome-looking armor or weapons.
