This HAS to be a RP thing for Jass.
Muru is the Naaru that gives the Blood Knights their power.
Unlike all the others though... Jass asked for his power not stole it.
As of patch 2.4 Nuru has been stolen... Infact... It's become a boss...
http://www.wowwiki.com/M%27uru_%28tactics%29
I had it so Jass could hear Muru's Song when he was channeling his powers... Now it's been twisted he will loose this. As a result he will want to go explore... So onn to Sunwell Plateau.