[RPG] Can an animated sword, made of adamantine, take damage via magical fire


During our game, the DM claimed that a sword forged of adamantine would not take any damage from a spell's magical fire. In this instance, it was an animated sword that attacked us, and therefore a creature, no longer just an object. His rationale was that once forged, only certain kinds of damage would affect it, and fire damage was not among them. Does this ruling have a factual basis?

Best Answer

This ruling isn't "standard" D&D5e. (Assuming the GM was using the Flying Sword as presented in the Monster Manual.)

(Of course, this effectively is a homebrewed animated sword. In which case the GM is free to give it whatever damage immunities they would like.)

The Flying Sword (MM p.20) has no immunity to fire. (It is immune to poison and psychic damage, so even in that stat block we can see it'd have been easy to add "fire" to that list, but the developers didn't.)

Additionally, adamantium in 5e traditionally grants the nullification of critical hits, rather than immunity to fire. See DMG p.150, for example.

That said, I've seen this sort of misunderstanding/mistake/mismatch in expectations cause too much grief at tables. I strongly recommend that out of session you take a moment to ask the GM about it, rather than let it fester. And that conversation doesn't have to be confrontational: "hey, that's neat that some materials grant fire immunity--can I quest for some of that and have it crafted into a shield?" can work just as well as "oh, so I guess I'm going to have to have cantrips ready to deal two different damage types, now?"