As many of you know, Ed has recently stated that in Rebirth (the upcoming BoI remake expansion) soul hearts will not be able to go off the screen. This is a huge gameplay change, and it essentially caps the maximum number of hearts at 12.

However, this change will also change how players approach soul hearts. In the game as it is now, soul hearts are always useful but hard to replenish under normal circumstances. Now it is as if each new red heart container effectively removes your ability to hold another soul heart. If you're full on soul hearts and another drops you'll just leave it instead of greedily gobbling it up, and later you may backtrack for it if you need it. Just like a red heart.

See? The limit of 12 hearts max takes away some of the unique gameplay features of soul hearts, and makes them more like red hearts in terms of gameplay.

But, in the spirit of balance, soul hearts need to be tweaked. Guppy's paw or the habit book of revelations can easily break the game. What if, instead of limiting total number of hearts to 12, activated items that gave soul hearts wouldn't activate? Instead your heart containers would flash, indicating that the item cannot activate while they're full. This prevents you from using book of revelations a thousand times, but will still let you pick up soul hearts from random drops.

There are some caveats. The nail should still increase damage, but the flashing heart screen would indicate that no spirit heart is being given. The relic and the mitre could have reduced (or zero) chance of paying out with a soul heart when your hearts are full, and same goes for the crystal ball. Guppy's paw should be allowed to activate if you have 11/12 hearts, with the spillover going off the screen. Then, once this is done you would be unable to continue activating the item until your hearts are no longer at 12 or higher.

Perhaps this solution is more confusing. Ed himself said that he likes the mystery that having hearts off the screen provides, not knowing how much health you have left. But who am I kidding? Ed is set on limiting Rebirth to 12 hearts maximum and when Ed is set on something it's impossible to convince him otherwise. But, I suppose I'll be sad to see soul-hearts-of-the-screen go. We've had a good run... snif