There are augments for character gear that give out heart bonuses for doing a mercy. If you've done a bunch of towers, some AI team battles, and unlocked stuff in the Krypt, you might have some useful ones for your main.
For Scorpion, I have the spear augment that gives out 9% additional hearts for doing a mercy, as well as an augment that gives out 9% additional hearts for doing a mercy and then a brutality.
You normally get 3 hearts for a fatality and 5 hearts for a brutality.
During my testing, I got 8 hearts for doing a mercy and brutality (as well as 12 souls instead of 10 for some reason) with one of those bonus augments equipped, and another 2 hearts with two of the bonus augments equipped.
Since some of the later character towers require brutalities to progress, might as well load up a Klassic Tower on Very Easy (after unlocking the character tower) to fulfill those requirements and stock up.
For Scorpion, I have the spear augment that gives out 9% additional hearts for doing a mercy, as well as an augment that gives out 9% additional hearts for doing a mercy and then a brutality.
You normally get 3 hearts for a fatality and 5 hearts for a brutality.
During my testing, I got 8 hearts for doing a mercy and brutality (as well as 12 souls instead of 10 for some reason) with one of those bonus augments equipped, and another 2 hearts with two of the bonus augments equipped.
Since some of the later character towers require brutalities to progress, might as well load up a Klassic Tower on Very Easy (after unlocking the character tower) to fulfill those requirements and stock up.