Tbh, I find that meter pretty much useless.
First at all, new cards is rarely taken into account - so it seems that Zanz doesn't care too much about the fact that it's inaccurate (SoFr is a new mechanic, it's ignored. SoW as well).
Second at all, there are already several things that breaks it. Momentum, adrenaline, antimatter, purify counters, you get the point..
What about either remove it completly, or make it update on the fly at the actual output?
Let's say this; you play cards, the damage meter internally run "end turn" to see your theoretical maximal damage output as how it is right now. (maximal as in, SoFr always crits, Dusk Shield never protects, etc).
Also would be nice to have another color for the damage meter (blue or anything?) that shows up when the damage you do per turn is negative (accomplished by antimattered things or purify counters)