I find that Cold One Cav are great against normal infantry, e.g High Elf Spearmen, Clan Rats, Marauders and the like. A added Scar-Vet or Oldblood can also enhance the unit so that it can hold its own against other units. I generally take 5 Cold One Cav, a scar-vet and oldblood in the same unit and smash anything that gets in my way.Th Cold One Cav beat normal guys, the Scar-vet and Oldblood beat up other stuff like other calvary or elite units (with the right upgrades.) Also, try Lore of Light. Weapon Skill 10 spell, phas protection and timewarp make the unit nigh unstoppable.