Prince Liam seems cool with Hakkar, but having no way of triggering Hakkar immediatly seems like way too risky. 10-mana Hakkar being transformed or silenced hurts a lot.

Yes, Umbra + Crasher + no other DR minion = guaranteed blood.
Also yes, Hemet is in to blow up your own blood.
Archbishop is often enough to win the blood war, similar to the Warrior Hakkar deck with Dead Man’s Hand, but Hemet gives you a nice way to ensure you don’t die to it. Be careful not to blow up your own library too early and die to fatigue though.