oak hound
If you equip Primeval Northern Heart, your Hearts go to 5. If you then equip Firstborn Emerald Heart, your Hearts do not go back to 4 as they should. They stay at 5. This might work with other combinations of Northern Heart + some other heart but not sure, haven't tested.
nova sand
what is emerald heart combined with?
oak hound
flesh magnet
nova sand
ok so emerald + ruby
sturdy shuttle
This happens with other hearts as well. The workaround for now is to equip a different heart with the same amount of charges first