The cool part about the BR is that he's essentially a kamikaze warrior. You run in there, do some damage, get swarmed by heroes and spawns, blow up while taking down 2-3 heroes with you, reincarnate, get your ass out.
The main problem about the BR is that he's one of the slowest heroes in the game and with an even slower attack cooldown, therefore he's garbage without Battle Rage on.
Best way to kill a hero with Battle Rager: Get Boots of Sprinter, period. That thing is SO awesome, it lets you run around and rape heroes no matter how far they run or how much life they have. You put on Battle Rage, attack a hero with middle to low hp and when he starts running click Boots of Sprinter and you don't even need to stun him with Bash to kill him.
Another way is to solo a hero, bring him down to low hp with rage, blow up, reincarnate= GG PWNED
I love it when Jimmy dies to that, it brings a tear to my eye.
"I shall be unfettered by all, to roam across the frontier of my world casting conformity and society to the wayside. I will let my name represent an emancipation from the confines of what others desire me to become or conform. My voice will echo across the lands and times where seekers raise an ear. I am the beginning and the end, the part and the whole."