Should he recognize a rust monster? (Savage Tide Mild Spoiler)

[Fifth Element]

The knowledge (dungeoneering) skill specifically allows you to recognize aberrations. DC 10 (for easy) should let him know that this monster destroys metal. Personally, I think I'd let the guy make an untrained skill check for this one. It's more fun that way.

Per the rules it would be a Knowledge (dungeoneering) check versus DC 15 (10 + HD). Untrained Knowledge skill checks can only be used for common knowledge - maximum DC of 10. So technically, he should not get the roll.

But as P-Cats says, it would be more fun to allow the roll. Give the fighter a chance.

Or, if you think players will be upset by losing precious items, perhaps a rust monster is not a good opponent for them.

 

[Numion]

Give a description, don't show a picture, give the PCs advance warning of the monster. Like the normal signs I suspect the monster would leave: rusted stuff in previous rooms / places.

With this combo they might get an idea before hand by metagame (from the description), in-game (rust), or maybe not. It's not the end of the world if they aren't surprised by the rust attack, and you'll cover your behind by having the possibility of warning beforehand.

 

[carborundum]

Or, if you think players will be upset by losing precious items, perhaps a rust monster is not a good opponent for them.

I've decided to start throwing stuff that does lasting damage at these guys, oozes, diseases, shatter spells, sunder attempts and rust monsters. It's a breath of fresh air, I tell you!

To be honest, it's not that they'd be angry, more that they would suddenly announce rule 11b(iv) subsection 3 whereby he should have had (for example) an untrained knowledge check to recognize it from stories since he worked in a bar for two years as noted on page 11 of his character background.

An exaggeration, but I'd hate to have to retcon a dramatic scene becase I missed a rule somewhere.

 

[Greg K]

I think there are a few assumptions being made

1) Rust monsters are common
2) Everyone should have heard of rust monsters
3) The world of DND

The OP needs to decide how common or rare rust monsters are in the world he is running and begin from there.

 

[Drowbane]

This really depends on the campaign.

Knowledge (dungeoning) exists for a reason (and in my campaigns, there is no such thing as "Class Skill").

 

[maggot]

I agree with a Knowledge (dungeoning) check. If you don't go that way, what is the point of taking the skill. This is the one case where it is useful. If you are very generous, let the fighter roll untrained. But still you are hosing the guy that spends two skill points to buy a Knowledge skill cross class just so he can make these types of rolls.

 

[WayneLigon]

Any tips for handling such a situation, folks?

Honestly, my best advice would be just not to use that monster. I can't remember the last time I bothered with it. It's funny to use, once ever, and then never again.

 

[Semah G Noj]

I think it was Lore from The Ratings who said (And I'm paraphrasing)
The notion that "if your character has not seen a thing then he can't know what it is" is a bit ludacrous. I mean, I'm sure that at some point during paladin school, the teacher would have shown the drawing from the 1st ed Monster Manual and said "If you ever see one of these, send the squire in with the wooden staff."

 

[Bladesong]

Not unless he has witnessed one before. Only someone with the knowledge check should get a roll. If you wanted to be really generous give him a DC 20 intelligence check to remember something he heard once, but no details ... i.e. a creature that "eats" metal perhaps.
The following was an update on the Rust Monster from ...somewhere (maybe the official site); perhaps you could use it instead and maybe make it look different (couple of tentacles rather than antennae )

RUST MONSTER CR 3
Medium Aberration
Init +3; Senses darkvision 60 ft., scent; Listen +1, Spot +1

AC 18, touch 13, flat-footed 15
hp 27 (5 HD)
Fort +2, Ref +4, Will +5

Speed 40 ft. (8 squares), climb 40 ft.
Melee antennae touch +7 (rust) and
bite +5 (1d6+2)
Space 5 ft.; Reach 5 ft.
Base Atk +3; Grp +3

Abilities Str 14, Dex 17, Con 13, Int 2, Wis 13, Cha 8
Feats Multiattack, Weapon Finesse
Skills Climb +10, Hide +7, Move Silently +7

Rust (Su): A rust monster that makes a successful touch attack with its antennae causes the target metal to corrode, warp, and crack. Any metal weapons, armor, and shields carried by a creature struck are weakened by this effect. The bonus to AC provided by an armor or shield drops by 2, to a minimum of 0. Weapons suffer a –2 penalty on attacks and damage, with a maximum penalty of –6. Magic armor and weapons, and other magic items made of metal, must succeed on a DC 17 Reflex save or be dissolved. The save DC is Constitution-based and includes a +4 racial bonus.

These penalties last for 10 minutes. A rust monster that spends 5 minutes devouring a metal object (whether magical or mundane) transforms it into rust, destroying it permanently.

A metal weapon that deals damage to a rust monster also suffers this warping and corroding effect. Wooden, stone, and other nonmetallic weapons are unaffected.

 

[Greg K]

I think it was Lore from The Ratings who said (And I'm paraphrasing)
The notion that "if your character has not seen a thing then he can't know what it is" is a bit ludacrous. I mean, I'm sure that at some point during paladin school, the teacher would have shown the drawing from the 1st ed Monster Manual and said "If you ever see one of these, send the squire in with the wooden staff."

Except that you are assuming that they have been encountered before. Maybe in the setting, they are extremely rare or unique having been some wizard's mad creation existing that nobody has encountered (look at the several new species of creatures discovered in our world just a month or two ago). In such a case, I think it would be ludicrous to asssume that anybody in the Paladin school has necessarily encountered let alone heard of them.