They made that as a goblin already, and its ruining the tournament environment only less so than Ravager Affinity. I know you love your Pestilence, but making a rat version is silly.
As for pump, it seems the only way to make using a lord worthwhile. As they are, the Relentless Rats coming out will make use of any other rat pointless, since they only water down their power. Chittering and Ravenous's abilities aside, all other rats are totally pointless. Therefore, a lord of "tribal uniter" card would need to make using any old rat card worth it. Only way to do that is with something along the lines of Coat of Arms. That's why I put the pump ability on, and had such a huge cost for a 3/3.
Any other ability, and you should just use Relentless Rats. "Oh, this lord gives Rats fear. Um, not gonna scrap those four Relentless Rats to pop in four Plague Rats." See what I mean about the importance of the Coat-like pump? Plus, the Coat-like pump is really, really in favor with rats historically--Plague Rats, Pestilence Rats, Swarm of Rats, and now Relentless Rats.