Wouldnt your first blood trigger give your killing spree trigger problems? When you set Kills_KillingSpree to be True (this part)
Code:Set Kills_KillingSpree[(Player number of (Owner of (Killing unit)))] = True
When you set it to true the next person who kills a unit will get a killing spree because your variable was defined as true from the person who made First blood.
i can write that triggers in only 3 (init,firstblood,normalkills)
look above, how did he make a background of that trigger