(1) Real-time evolution during battle.
(2) Availability of Heart Scales.
So don't get confused.
On the topic of Heart Scales, it was actually sold on Black City for P10,000.
But that place is greedy. I think P1,000-P1,500 would be good.
Also, I don't see it being sold on ordinary places.
Probably just from a lone merchant that sells rare stuff, or one of the prizes you can exchange in some facility.