Iron Golem

Golem Antimagic — Harmed by acid (6d10 untyped, 2d8 untyped from areas or persistent damage); healed by fire (area 2d8 healing HP); slowed by electricity
A golem is immune to spells and magical abilities other than its own, but each type of golem is affected by a few types of magic in special ways. These exceptions are listed in shortened form in the golem's stat block, with the full rules appearing here. If an entry lists multiple types (such as "cold and water"), either type of spell can affect the golem.

Harmed By Any magic of this type that targets the golem causes it to take the listed amount of damage (this damage has no type) instead of the usual effect. If the golem starts its turn in an area of magic of this type or is affected by a persistent effect of the appropriate type, it takes the damage listed in the parenthetical.

Healed By Any magic of this type that targets the golem makes the golem lose the slowed condition and gain HP equal to half the damage the spell would have dealt. If the golem starts its turn in an area of this type of magic, it gains the HP listed in the parenthetical.

Slowed By Any magic of this type that targets the golem causes it to be Slowed 1 for 2d6 rounds instead of the usual effect. If the golem starts its turn in an area of this type of magic, it's slowed 1 for that round.

Vulnerable To Each golem is vulnerable to one or more specific spells, with the effects described in its stat block.

Vulnerable to Neutralize Poison — Casting Cleanse Affliction on the golem deactivates its Breath Weapon for 1 minute.

Vulnerable to Rust — Magical rusting effects, like a rust monster's antennae, affect the iron golem normally.

Breath Weapon (arcane, poison) — The iron golem exhales poisonous gas in a 10-foot burst{10-foot radius} centered on the corner of one of the iron golem's squares.

The gas persists for 1 round. Any creature in the area (or that later enters the area) is exposed to the iron golem's poison.

The golem can't use its Breath Weapon again for 1d4 rounds.

Inexorable March — DC 37 Fortitude

On a critical success, the resisting creature takes no damage; otherwise it is damaged as if hit by the golem's fist.

The golem Strides up to its Speed, pushing back each creature whose space it moves into and damaging them if they try to stop its movement. A creature can attempt to bar the way by succeeding at a Fortitude save.

Iron Golem Poison (poison) — Any Drained value from this poison is reduced by 1 every hour.

Saving Throw DC 33 Fortitude

Maximum Duration 4 rounds

Stage 1 2d6 poison damage and Drained 1 (1 round)

Stage 2 4d6 poison damage and Drained 2 (1 round)

Stage 3 8d6 poison damage and Drained 3 (1 round)