On last turn you need Cú Chulainn and Blue eyes on the field together and do the following steps:
-Activate secret pass on Cú Chulainn
-Use Gift of the Martyr on Blue eyes
-Activate Cú Chulainn's effect using Blue eyes
-Activate both ritual weapons
-Use Riryoku to give Cú Chulainn another 500 atk points
Also, you don't need Nobleman of extermination, Des counterblow, Jar of greed or Soul exchange. Riryoku can be changed for any card that increases Cú Chulainn atk by at least 500.
Forget what I said, you have to watch out for one of Pegasus' monsters that won't allow you to attack on summon. I suggest at least a "Murmur of the Forest" to negate its effect.