Well no wonder, that's simply a really strong and efficient deck! :)
But I agree that this archetype is a bit too easy to build for the power output it has. I'm not 100% sure to nerf Force Multiplier just yet. The card is pretty hard to balance because it has a hard cut-off between doing nothing and doing something very powerful. And you managed to upgrade your weapons to a point where you meet the threshold very consistently.
I was already planning to nerf the Lance, because it currently scales just too well with upgrades and the diagonal attack option is a crazy powerful effect already. And it seems it was your main damage source in this case.
This is amazing feedback, thank you so much!