Angel Room can show instead of Evil Room up after defeating floor Boss, when players faith is high enough (Faith Up items). Inside the Angel room there will either be a faith related item, 3 spirit hearts, or 2 eternal hearts. Certain items such as sacred heart, godhead, breath of life, etc. can only be found inside angel rooms. If you have defeated ??? or the lamb you can bomb these statues and they will become a boss that you can kill to obtain a key piece. These pieces are used to open the large golden door in the chest or the dark room. If you re-roll the key pieces with the D6 or a Perthro rune, then you will get a faith related item. You can use that trick every time you get an angel room as long as you don't collect the 2nd key piece.