Complex sentence: Through the Frostwolf Clan's current chieftain Drek'thar, Thrall learned the ways of the shaman, and being naturally talented he eventually became the greatest shaman alive on Azeroth.
Split into simpler sentences: Through the Frostwolf chieftain, Drek'Thar, Thrall learned the ways of the shaman. Being naturally talented, he eventually became the greatest shaman on Azeroth.