D&D 3.5: Polymorphed Rust Monster vs. Iron Golem

Question

GMs hate me because of my sheer resourcefulness. This situation presented itself during a 3.0 game, and I'm wondering how it would play out in a 3.5 game. The party was attacked by an iron golem. I polymorphed my familiar into a rust monster and instructed it to use its rust touch attack on the iron golem. What would happen under the 3.5 rules? As I recall under 3.0, the rust attack was of the appropriate type to be transfered and available to the polymorphed creature. The rust attack in 3.0 would instantly destroy a cubic meter of ferrous metal per round, so the iron golem shouldn't last more than a round or two.

Someone please add "polymorph" as a tag to this post. I'm unable to create new tags at this point.

Answer 1

First, from the SRD:

Rust (Ex): A rust monster that makes a successful touch attack with its antennae causes the target metal to corrode, falling to pieces and becoming useless immediately. The touch can destroy up to a 10-foot cube of metal instantly. Magic armor and weapons, and other magic items made of metal, must succeed on a DC 17 Reflex save or be dissolved.

Iron Golems are not magic items, Unless you interpret Craft Construct to mean they are. If they are magic items, they recieve a DC 17 reflex save or instantly die.

As for if your Familiar could be polymorphed to have Rust:

Polymorph: This spell functions like alter self, ... It also gains all extraordinary special attacks possessed by the form but does not gain the extraordinary special qualities possessed by the new form or any supernatural or spell-like abilities.

Rust is an Ex special attack and could be gained.

Answer 2

Although the iron golem is specifically described as being affected normally by a rust monster's Rust attack, the effect of the Rust attack on a creature isn't explicitly given. Since it instantly destroys a 10-foot cube of iron, it would be reasonable to treat it as a disintegrate spell, dealing 2d6 damage per hit die of the familiar (i.e. your caster level). As magic armour is allowed Reflex save (DC 15 + half the rust monster's hit dice) against the Rust attack, it would be fair to offer the iron golem the same option.

In fact, you can polymorph yourself into a rust monster, and opt to have the spell also affect your familiar, bringing two rust monsters into play.

Both the rust monster and his rust attack are still valid options with the 3.5 polymorph spell, as the rust monster is a 5HD Medium aberration and the Rust ability is an Extraordinary special attack. To use this on your familiar, he must be at least Small size (the new form can only be within one size category of the creature, a limitation the 3.5 polymorph spell inherits from from alter self).