Hmmm....not unexpected
I tend to run MoR/MB/Tenais/FS/Liquid Flame. In my experience (and I've run dual heats/Rodgorts Invocation spam etc), this setup does work. As long as you can hit a reasonable mass with MoR, FS is effective at triggering it. Sure, you may get some scatter, but even with that, you tend to get the idiot AI wandering back into the AoE and retriggering burning

Add to that the effects of your heat and Liquid Flame and you have quite a nice DoT effect with a fair bit of mass spike damage from LF. MB keeps the energy up as long as you target it at the right target. As an option I also run TNTF (at Sunspear rank 9).
I don't claim it's the ultimate cookie cutter "success" build, but give it a try, you might like it.