As for me it seems that it's not right that when you spill big amount of blood into water, water is still clear without any traces of blood. So I propose that if you spill blood into the liquid, the whole flooded area blood counter increases and liquid counter decreases. When there is more blood than liquid, half of the liquid turns into blood, which has the same properties as the water, only colored in red. When there is no liquid in the area, it completely turns into blood. And also, when you spill enough blood onto the ordinary floor, it also turns into blood. Gibbed enemies drop massive amount of blood, instantly turning the cell into blood. Lost Souls and Pain Elementals do not spill blood.
This might need some balancing, because it makes N! easier and viles weaker and Mortuary easier. But it adds some flavor and makes lava and acid areas crossable.