Help!

I am looking for this action fantasy manga i read a hella long time ago
So its goes..
A young mans brother had climbed the tower as one of the top rankers
His team was very strong and set records throughout the tower
But when the younger brother is home one day he is given his eldest brothers watch and told his brother died in the tower
In that watch is the memories of his brother and each of the ways his comrads betrayed him, he gives his talent to his younger brother who choses to climb the tower to avenge his brother
The younger brother is identical to his brother and hides his face so his eldest brother’s comrades do not recongnize him.
If i recall correctly his hidden talent had something to do with dragons blood?

Thanks in advance!