CommentPlus is a feature designed to encourage members to leave SoundCloud comments when they repost a track.
It is an option when you submit a Direct Request or start a Campaign.
When a member chooses to repost your track, they will be offered an extra 2 credits to leave a comment. It is optional and they can choose not to.
In the case of Campaigns, 2 credits will be removed from your budget each time a member leaves a comment.