Stats

Stats are aspects that affect encounters. Most stats increase as one's LV rises, although other methods can increase the stats.

HP
Hit Points or Health Points—it has also been abbreviated for Horsepower or Hit Poodles by Chara—(HP) is the level of endurance that determines the damage someone can take before dying. Maximum HP varies depending on the person and increases when their LV does. Resting or sleeping fully heals and raises HP 10 points above its cap. HP can also be restored through consumable items or interacting with a SAVE Point.

An attack hitting the receiving party lowers their HP. The loss is dependent on the attacking party's Attack and the party of receipt's Defense. Upon reaching 0 HP, a determined human or Boss Monster's SOUL snaps in half and shatters, sending the former to the Void where they can reload their SAVE. If a monster's HP reaches 0, they disintegrate into dust and reward their killer with EXP and money.

ATK
Attack (ATK) determines the damage output of the attacking party. Someone's base ATK increases with LV and equipping a weapon. ATK can be changed temporarily during battles with ACTs or consumables.

When someone's ATK is high enough, they can spare people without ACTing. This rule is true even of people that have a non-traditional sparing method: Toriel can be spared immediately, and the colored name and everything else shows if the total ATK is 20442 or higher.

DEF
Defense (DEF) determines the damage input for the defending party. Someone's base DEF increases with LV and equipping armor. DEF can be changed temporarily during battles with certain ACTs or consumables.

DEF is subtracted from the damage output of the attacking party. However, it cannot lower the damage that someone takes to a value less than 1.

If someone takes 0 or less damage from an attack, the attack's result is a miss, and negative damage values will restore their HP instead of damaging it.

EXP
Execution Points (EXP) are gained by killing people. When someone accumulates enough EXP, their LV increases. On some occasions, EXP is gained by attacking and sparing afterward and not necessarily killing.

The acronym is designed to mislead people, as in most cases, EXP stands for Experience Points. If Frisk "kills" Napstablook, they lose one "experience point", which does not affect their EXP and serves as an early clue that EXP are not Experience Points, but a different stat entirely.

LV
Level of Violence (LV or LOVE) increases HP, ATK, and DEF when it rises. Sans describes it as "A way of measuring someone's capacity to hurt." Everyone starts at LV 1 and can rise as far as 20. LV can be set arbitrarily high or low via file editing.

When someone enters a battle with an LV of 20, their ATK and DEF automatically sets to 30 and their maximum HP to 99. This change is never seen because the only instance of someone's LV getting to 20 is after Frisk's fight with Sans, who is the final opponent Frisk can practically fight.

INV
Invulnerability (INV) determines the number of frames an attack cannot hurt someone after they receive one. It is a hidden stat that someone can only increase through certain armor and weapons.

Invulnerability is set to 0 during fights with those who have the KARMA ability, such as Sans. The items and armor mentioned before will only increase INV by small fractions of a frame when battling said person.

SPEED
SPEED determines the velocity someone can move around the Bullet Board. It is a hidden stat that someone can modify temporarily only through certain items and ACTs, as well as in a battle with someone that has a thunder attack.

MDR
Murder Level (MDR) is an entirely internal statistic that tracks someone's progress while committing genocide. This statistic begins at 0 on every timeline and is reset by a simple Reset. The murder level is accessed a few times, notably to affect types of bosses encountered and boss activity, to find the correct ending to play depending on one's choices, and, in Frisk's SAVE file only, to decide whether or not Frisk battles Sans.

Flags in someone's SAVE file are accessed and used to determine the choices they have made and whether or not those choices fulfill the requirements for a complete or aborted genocide attempt. Except for the murder level override, each step increments the murder level only if all of the requirements preceding it have been fulfilled. For example, if Frisk has killed Toriel but did not exhaust the Ruins kill counter beforehand, the murder level remains at 0.

As an example, the line number listed below corresponds to the line number in Frisk's SAVE file, i.e. 31 greater than the flag number.

The murder level override is checked after this, ignoring the above calculation: Frisk battles Sans if the murder level is 16 or higher.