Daemon's Tail

Daemon's Tail is an unlockable trinket.

Effects

 * 80% of heart drops are replaced with keys.
 * All heart drops turn into Black Hearts, if possible. (Sometimes heart types are tied to the room, such as in certain Super Secret Rooms.)

Synergies

 * Black Feather: Black Feather grants a damage boost for Daemon's Tail, provided the player has an extra trinket slot or has gulped/smelted either of the trinkets.

Tips

 * Due to its specific mechanic, Daemon's Tail has no synergy with items increasing chances for Soul/Eternal/Black Hearts to drop instead of a Red Heart, like, Mom's Pearl, or Bible Tract.
 * Since the frequency of heart drops is lowered, holding this trinket can be dangerous to Isaac if he has numerous Red Heart containers, as he can easily find himself short on health.
 * This trinket is more effective for or, as they start with no Red Heart containers.
 * Mom's Pearl or Bible Tract are trinkets which only need to be held to be useful, whereas Daemon's Tail is more effective if it is held and dropped at the right times, to get an increased chance for consumables from certain mechanics (to counter a lack of bombs/keys/coins, or to get Black Heart protection), and to still get enough heart drops to stay alive at other times (from bosses or familiars).
 * This trinket nearly requires this kind of strategy to pay off, making it tough to use as the player will have to sort and remember the moments where they must pick up or drop the trinket, as it interacts with nearly every consumable dropping mechanic.