There are three types of enmity generation:
Damage Enmity is enmity stemming from damage dealt to the enemy. The multiplier for actions that say, “Increased Enmity” can be found in the “Increased Enmity” tab of the FFXIV - Tables spreadsheet (See Resources).
Healing Enmity is enmity generated by directly healing yourself or another player.
Action enmity is enmity generated by performing a buff or debuff that does not deal damage or directly heal a player. This is important when examining the difference between an action like 4.0 version of Elusive Jump and Lucid Dreaming. The former will simply cut your threat in half. The latter will cut your threat in half and then add enmity from gaining a buff.
∑ Status Effect M is the sum of all status effect multipliers involved. Multiple Enmity Modifiers stack additively.
If ( 1 + ∑ Status Effect M) is negative, your actions will only generate 1 point of enmity.
If an action has a damage and healing component, only the damage component will generate enmity.
All pets relay their enmity to the master now.
Damage Threat = ⌊ Damage × Increased Enmity ⌋ × ( 1 + ∑ Status Effect M ) ⌋
Spell Threat = ⌊ HP Restored / 2 ⌋ × ( 1 + ∑ Status Effect M ) ⌋ / # Aggroed Enemies ⌋
Abilities Threat = ⌊ HP Restored × 3 / 5 ⌋ × ( 1 + ∑ Status Effect M ) ⌋ / # Aggroed Enemies ⌋
This specifically refers to skills, such as Equilibrium and Second Wind, whose primary action is healing. It does not include indirect healing through Bloodbath or Synastry.
Buffs & Debuffs
Action Threat = ⌊ LevelLv, THREAT ⌋ × ( 1 + ∑ Status Effect M ) ⌋ / # Aggroed Enemies ⌋