In Dungeon Dice Monsters, HP, or Hit Points, are used to keep track of how much damage a monster has taken. A monster may only remain on the field if it has HP, and once its HP is reduced to 0 it is destroyed and removed from the field. Unlike Duel Monsters, a monster need not have more ATK than the defending monster's HP. HP damage is tracked with damage counters, which represent 10 HP each. As a monster accumulates Damage Counters, it loses HP. HP can only be restored by monster effects and special items.
HP can be reduced by monster attack, effects from monsters, or certain items. A monster may defend its HP by using Defense Crests, which reduce the damage taken by the monster's DEF. A monster may defend as many times as it is attacked, but can only use one defense crest at a time to reduce damage. In other words, a monster with 30 HP and 10 DEF can only defend against 10 ATK. If a monster attacks it with 30 ATK, it will only be reduced to 20, and the defending player cannot simply use 3 defense crests to reduce the damage to 0 (excepting any special effects).