we have to see what are the values.
I expect 100% spear mastery, 70% break, and 4x200% but could be low.
Im happy with only the 70% break. That would put elza in another level for OHKO runs
70% break is unrealistic. Beyond fantastic if that happens, but I'm pegging that at "all but 0%" chance of happening. Practically no one is expecting more than 60%, as she debuffs two stats (compared to Delita's one stat 65%). 70% (or even 65%) would immediately obsolete Delita's enhancements, which I doubt is the intention here.
Stat breaks are exponentially more powerful as they approach 100%. A 70% break would be bonkers and to balance against that, every serious boss would need defenses so high that without the break everyone is going to do damage in the hundreds or worse just to keep the OHKO teams away. (Bad enough as is and with Elza/Delita, it's only going to get worse).
50 --> 55 --> 60 is the most likely upgrade route.
100% spear mastery.... pretty much no one as far as I can see is expecting this.
Madness Rush.... everyone is also expecting 4x 200%.
The likely process for Elza is to chain Ravishing Blow to Madness Rush.
Now: (50% DEF break) [2x mod] --> 4.2x Madness Rush --> 840% RT effective damage
After: (60% DEF break) [2.5x mod] --> 8.0x Madness Rush --> 2000% RT effective damage.
So, you have massive damage, but at the expense of being un-chainable.
Also if you were to use the first hit of Madness rush as a chain finisher, you would get [2.5x mod] x [2.0x mod first hit] = 500% damage times chain bonus. Serviceable, I suppose.