Killing Rage Home Rule

It states in the rules that the Battlerager's killing rage can only be invoked after 5 rounds of singing or chanting. This makes it near impossible for Thorsan to actually use this ability on the board. In the spirit of gameplay, a rage can be invoked after one round if the party gains surprise on an opponent or after three rounds in standard combat. I believe that the rage itself has enough negative drawbacks along with the positive that this should only improve roleplay.