Why not 1 Dark Pact as a way to get Rin going against decks that probably run silence. Against Priest you can drop the combo turn 7 and start the Chain at turn 8 (hopefully). They don’t really pressure you with board presence and you are free to just cast 1 or even 2 Seals per turn. If you are fast enough and burn a key part of their combo it might be faster and more reliable then the rat.

I would say The Lich King might be a consideration. He has taunt, so potential another target for Ancestral Spirit and his card can potentially be better then random 8 dmg in a deck that’s defensive like this one.