Sharpclaw `Tuff` Grimefoot
From EZ Server Wiki
Boss in Sunderock Springs who is spawned at random by entering the active Open Portal in the zone. Entering the open portal will transport you to a random closed portal in the zone, and has an ultra rare chance of spawning Sharpclaw, he can also spawn from the death of the Bandit leaders. (Ro'kki and Little J'Haughn specifically).
Sharpclaw's soul, part of the Champion's Seal quest, is the one of the rarest of the souls you are required to collect, due to his rarity in spawning, and rarity in dropping the soul.