Bring a Blood Shard to Mangletooth in Camp Taurajo in the Barrens. Collect more Blood Shards if you want him to bless you with Agamaggan's power.
Along with the thorns, the blood affected <snort> other aspects of the earth: blood red stones mixed in with other minerals. The Bristleback dig up these shards and carry them as totems <snort> for strength in battle and as totems for their magics. <snort>
I know the secrets of that magic.
Bring Mangletooth one of these blood shards to show you understand. Bring Mangletooth many of the shards, and he will bless you with quilboar magic--the magic of Agamaggan! <snort>