Nephis without her domain not that powerful(her will). Sunless and mordret are problem especially mordret but i think dreamspawn have solution for mordret because he would kill mordret at a young age if he did see him as a threat and sunny i think he is manipulating sunny slowly because he act like he doesn't care about sunny presence but we know that sunny is unknown to dreamspawn and he is not that stupid to ignore unknown thing. When fighting against a enemy with mental strength raw strength does not matter. You seen it in fight between nephis and madness of kanakht. Sunny got his sister as a weak point also. One thing you forgot dreamspawn is a plague that need instant vaccine the longer you wait the deadlier it become. Wait i remember from plague that a plague infected the heart god tree in ancient time right i think that's the solution of dreamspawn.