Phoenix necklaces are necklaces that automatically restore the wearer's life points by 30% of maximum if they drop below 20% of the maximum. They only have one use, after which they are destroyed.
Example: a player with Constitution level 99 (9900 maximum life points without any equipment) gets hit for damage and thus gets their life points under 1980, the necklace will heal that player 2970 life points. If the player drops to 0 life points from above the 20% threshold, the player will instead die, leaving the necklace unused.
If life points drops below 10% in one hit after being above 20%, and the player is also wearing the ring of life, then the Phoenix necklace is activated first.
In the Duel Arena, the phoenix necklace is considered food. Therefore, it will produce no effect if the "No Food" option is toggled on during a duel. On the other hand, the necklace works in Dominion Tower fights with the "No Food" handicap active.