Mu Online Guide | Guardians - Creating Ghost Horse, Ice Dragon (Season 15) 

Hello! If you want to get an ice dragon, we recommend using the Ghost Horse +15. The chance of getting Ice Dragon will be 100%. If you use Ghost Horse +14, the chance of getting Ice Dragon will be 90%. If you combination fail, you will receive a Ghost Horse +0 and the meterals for the combination will disappear. Ghost Horse +15 - chance 100% Ghost Horse +14 - chance 90% Ghost Horse +13 - chance 80% Ghost Horse +12 - chance 70% Ghost Horse +11 - chance 60%

Guide is wrong, it shouldnt fail. Just that the Chances of getting Ice Dragon (Rare) which is the Red in color defer in % according to Ghost Horse level Getting Ice Dragon which is Blue is 100%