5e SRD >Creatures >

Perpetual Engine

Gargantuan mythic construct, lawful evil

Armor Class 30 (natural armor)
Hit Points 315 (18d20 + 126)
Speed 40 ft.

30 (+10) 4 (-3) 24 (+7) 14 (+2) 21 (+5) 1 (-5)

Saving Throws Str +20, Dex +7, Con +17, Int +12, Wis +15, Cha +5
Skills Perception +25
Damage Resistances bludgeoning, piercing, and slashing from non-Epic creatures
Damage Immunities poison, psychic
Condition Immunities charmed, frightened, stunned, unconscious
Senses darkvision 500 ft., passive Perception 35
Languages Binary
Challenge Mythic 4


  • Advanced Weaponry. The engine’s attacks are magical and have a +3 bonus to attack and damage rolls (included in their description).
  • Arcane Dynamo. When the engine is affected by a non-Epic spell, that spell’s caster must succeed on a DC 24 Intelligence, Wisdom, or Charisma saving throw (caster’s choice) or the spell fails and is absorbed by the engine. When the engine absorbs a spell in this manner, it deals additional arcane damage on the next successful attack it makes. This benefit is cumulative and lasts until the start of the engine’s next turn. The additional damage is 1d6 for a cantrip or 1st-level spell, plus 1d6 for each spell level above 1st.
  • Mythic Resistance. When the engine fails a saving throw, it can expend one of its unspent legendary actions to succeed instead.
  • Reconstruction Protocol. The engine is extraordinarily difficult to permanently damage. When the engine is reduced to 0 hit points, it is instead restored to its hit point maximum and gains one level of the damaged condition. If the engine starts its turn and has six or more levels of the damaged condition, it is slain. Additionally, the engine is immune to effects that would kill or destroy it (such as disintegrate or power word kill) so long as it has five or fewer levels of the damaged condition.


On initiative count 20 (losing initiative ties), the engine takes a mythic action to cause one of the following effects. The engine cannot cause the same effect twice in a row.

  • Lock On. The engine targets a creature it can see with its weaponry. Until the next initiative count 20 the target cannot be hidden or invisible from the engine, and the engine’s attacks score a critical hit on an attack roll of 16-20. Additionally, the engine cannot attack another creature unless it is unable to attack its target.
  • Radiation Cloud. The engine emits of cloud of magical toxins in a 120-foot-radius sphere. Until the next initiative count 20 the area is heavily obscured, and creatures in the area have disadvantage on Intelligence, Wisdom, and Charisma saving throws.


  • Multiattack. The engine makes two Cataclysm Rocket or Pound attacks and either uses Acid Sprayer, Booster Engines, Lightning Harpoon, Power Slam, or Sonic Cannon action.
  • Acid Sprayer. The engine sprays poisonous acid in a 30-foot cone. Each creature in the area must succeed on a DC 24 Constitution saving throw or take 54 (12d8) acid damage and become poisoned. Additionally, the ground in the affected area becomes difficult terrain unless it is immune to acid damage.
  • Booster Engines. The engine gains a fly speed of 90 feet until the end of its next turn.
  • Cataclysm Rocket. Ranged Weapon Attack: +10 to hit, range 1,000 ft., each target in a 25-ft. cube the engine can see. Hit: 25 (4d10 + 3) fire damage.
  • Lightning Harpoon. Ranged Spell Attack: +15 to hit, range 120 ft., one creature. Hit: 31 (4d12 + 5) lightning damage, and the target is impaled by a harpoon on the end of a long chain. A creature so impaled cannot move or be moved away from the engine (including via magical teleportation). Additionally, at the end of each of its turns a creature so impaled takes 31 (4d12 + 5) lightning damage and is pulled 30 feet toward the engine. A creature can remove the harpoon by taking an action to succeed on a DC 24 Strength (Athletics) check. If the creature is ever more than 120 feet away from the engine, the impalement ends.
  • Pound. Melee Weapon Attack: +23 to hit, reach 15 ft., one target. Hit: 40 (6d8 + 13) bludgeoning damage.
  • Power Slam. The engine moves up to double its speed in a straight line. If the engine would move into a creature’s space as a part of this movement, the creature must attempt a DC 24 Dexterity saving throw. On a success, the creature moves to the nearest unoccupied space out of the path of engine. On a failure, the creature is pushed ahead of the engine as it travels, takes 35 (10d6) bludgeoning damage, and is stunned until the start of its next turn. If the engine encounters an object that would prevent the movement from this action, the object takes 70 (20d6) bludgeoning damage. If this damage destroys the object, the engine continues on its path.
  • Rapid Repair (Recharge 6). The engine magically regains hit points equal to its hit point maximum.
  • Sonic Cannon. The engine fires a line of concentrated sound in a 300 ft. line that is 5 ft. wide. Creatures in the affected area must succeed on a DC 24 Constitution saving throw or take 55 (10d10) thunder damage and be deafened. A successful save halves the damage and prevents being deafened.


The engine can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The engine regains spent legendary actions at the start of its turn.

  • Advanced Weaponry (Costs 2 Actions). The engine uses its Acid Sprayer, Booster Engines, Lightning Harpoon, Power Slam, or Sonic Cannon action.
  • Assault. The engine makes a Cataclysm Rocket or Pound attack.
  • Dispelling Burst. The engine ends any non-Epic spells or magical effects within a 10-foot-radius sphere centered on it.
  • Reengage. The engine moves up to its speed.
Section 15: Copyright Notice

Epic Legacy Campaign Codex Copyright 2020 2CGaming, LLC Author Ryan Servis

This is not the complete section 15 entry - see the full license for this page