I like the idea but the LB in support stance sounds like a ultra overpowerd tank LB. Tank LB wears off after a few seconds so regardless what rank, so a rank 3 LB from the Dancer should just do invincible for max 5 secs at highest. The LB should be more like buffing the group or it will compete to much with the tanks LB.
If the dances and other stuff is well thought and balanced it could be a good melee supporter.