The deadliest CR 18 in the world, courtesy of WotC

[the Jester]

A buffed cleric stepping out of a maze versus a dragon isn't going to survive. Trust me on this (or ask my players ).

That's what I like about you, James (well, aside from the fact that we're both Jameses). High fatality rate.

On topic, I'd say that the steel dragon as presented is definitely higher than CR 18, but I've noticed a tendency when running pcs around that level- they start being able to handle much tougher stuff than you'd expect.

I'd give it about CR 21, personally, based on the (very good, imho) rule of thumb that creatures that have caster levels should have a CR at least equal to their caster level.

 

[James McMurray]

When the party is getting True Resurrection for free because of the Ignore Material Components epic feat, death is the least of their worries.

 

[psyronin]

If its silent and still, it can't be identified via spellcraft.

Tome & Blood says silent still spells can be identified. 3.0 or 3.5, it boils down to a DM decision on the content allowable from that splatbook.

 

[reiella]

Tome & Blood says silent still spells can be identified. 3.0 or 3.5, it boils down to a DM decision on the content allowable from that splatbook.

Erm, I think that falls under Variant Rules or Precedence.

Especially given that the text about Identifying Spells is in the 3.0 PH as well.

Given that it directly conflcts with the core text, I'd say at best it's a Variant, albiet one that isn't labeled as such. It is an interesting variant at least (each item unable to discern increases the DC by +2).

 

[Wrahn]

Any DM who let's you waltz into a dragon's lair and suprise a creature of superhuman intelligence and wisdom is giving you a freebie. (Extraordinary circumstances withstanding of course, no one can think of everything, but expecting to suprise such a creature is expecting a lot.)

I think a more likely scenario is as the players enter the lair of the dragon (fully buffed and prepared) they get initiative and do the forcecage, silence (and heck throw in a quickened dimensional anchor/lock as well).

The Dragon response by shapeshifting as a free action (it had previously cast the spell, it lasts 10 min/level) into a pixie, slipping through the bars and behind a wall (I did mention this is it's lair didn't I). It then Gates in a Solar to deal with these obvious well prepared interlopers (attacking a goodish dragon, for shame).

At this point it is very clear that the encounter has escalated far beyond CR18 and is about to enter the TPK range. That is round one. Counting on helplessness from your enemy on it's home terrain is not something I would consider a survival trait.

 

[Majere]

Any DM who let's you waltz into a dragon's lair and suprise a creature of superhuman intelligence and wisdom is giving you a freebie. (Extraordinary circumstances withstanding of course, no one can think of everything, but expecting to suprise such a creature is expecting a lot.)

I think a more likely scenario is as the players enter the lair of the dragon (fully buffed and prepared) they get initiative and do the forcecage, silence (and heck throw in a quickened dimensional anchor/lock as well).

The Dragon response by shapeshifting as a free action (it had previously cast the spell, it lasts 10 min/level) into a pixie, slipping through the bars and behind a wall (I did mention this is it's lair didn't I). It then Gates in a Solar to deal with these obvious well prepared interlopers (attacking a goodish dragon, for shame).

At this point it is very clear that the encounter has escalated far beyond CR18 and is about to enter the TPK range. That is round one. Counting on helplessness from your enemy on it's home terrain is not something I would consider a survival trait.

What you are assuming here is that it cast shapechange previously.
Why ?

And none of this is anything a level 7 mage couldnt do
And he is only CR17

Once anyone gets level 9 spells then every combat is a potential TPK..
And Its almost impossible to stop any BBEG teleporting/gateing etc away

Equally as long as the party cleric has astral learnt its merely a matter of making sure he escapes to true ress everyone to then get everyone back.

High level D&D is a frankly strange and unwieldy beast.
Just because its nasty doesnt realyl prove anything. The best argument for making it CR21 is that it casts as a sorcerer 21.
Note this is NOT the same as having 21 levels in sorcerer. (Pedantry but an valid point)

Once you hit 9th level spells you really hit the limit, so anything in the 17-20 range of CR's is:
1) VERY daingerous
2) killable by a level 17 party

1 Question for all the people whining that my plan neesd a very specific conditions to happen.
What precisely can a level 20 party do that is so much more powerful than a level 18 party. What can they do that will make a significant impact unpon this encounter ?

Well ?

A level 20 party will have exactly the same resourses and problems as a level 18 give or take 1/2 spell slots. And I highly doubt the ocmbat will last long enough for 1/2 slots to matter.

So we can have this argument even if you make it CR 20, 21 or 23
The fact is that over CR 17 all mobs are more or less killable by a level 17 party until you start playing epic D&D.

Majere

 

[James McMurray]

Which is probably why people are putting this beast's CR above 20. It'll most likely require epic resources to combat.

 

[Azalnubizar]

I agree with Majere here.

Setting up possible szenarios what pcs might do or how the dragon might react doesn't prove anything here - really.

The player characters can do everything that the dragon can - and maybe four times...

So the dragon conjures a solar - maybe we have four clerics in our party, conjuring four solars?
Even if you assume the standard group: 1 wizard, 1 fighter, 1 rogue & 1 cleric you cannot start to predict what might be happening.
Every spell the beast launches can be countered or payed back with the same and more...

yes, I agree, that this monster is very tough and can be very tricky to beat, but just because most of the scenarios you can think of result in disaster, doesn't mean there is a wrong CR.
In my experience, player characters tend to come up with a set of very nasty surprises and, as already mentioned by Majere, every monster of CR 17+ is supposed to become a possible TPK.

I am pretty sure, that if you give your players time to set up a group of 18th level characters and tell them, what creature they are up against (so they can prepare - if you go into a lair of a nearly epic dragon, you do NOT go unprepared) you will have a 50%+ success rate... just try it.

And this is with characters set up from the spot. Most players grow with their characters. I did not know the wizard spells as well as the player I once had, who played an 18th level wizard. This means - players that play their characters from low level to high level often develop much better tactics, than characters that are made 18th level from the spot.

What you should not forget is, that a group of four characters has four full actions per round - the dragon doesn't.

Try to take an 18th level group against the beast and prove me wrong.

Azal

 

[UltimaGabe]

I would like to point everyone's attention to any other CR 18 in the monster manual. For a real comparison- let's look at a Mature Adult red dragon.

A mature adult red dragon is also a CR 18, but look at its stats. It's got 2/3 the HP of a Steel Dragon Great Wyrm, about 10 lower AC (can't remember the exact number, I don't have my MM handy), one Breath weapon (a cone of fire, DC lower than the Steel Dragon's, but does more damage), lower caster level (I believe it's a 13, I could be wrong), and lower Spell Resistance (I think it's somewhere in the 20's). It also has about 2/3 the Base Attack and about 2/3 the saves. The only advantages it could possibly have over the Steel Dragon is its single Breath Weapon does more damage, and it has a couple Spell-Like Abilities that, depending on the situation, could be more useful. But is a Breath Weapon worth half more hit points, half more base attack, half more Base Attack and saves, and almost twice the Spell Resistance and Caster level? One can cast 9th-level spells and can't be affected by 1st-4th level spells. The other does a bit more damage with his breath weapon.

Both are dragons, and both are huge. One is obviously highly superior (the Steel Dragon). The Steel Dragon would also defeat the Red Dragon in every single head-to-head battle, and neither has any weakness to the other. And yet they're the same CR?

 

[Wrahn]

What you are assuming here is that it cast shapechange previously.
Why ?

You are assuming that you can catch the dragon unaware. Why? Most of the dragon encounters I have faced have been on the dragons terms, not mine and the few that we have gone after the dragon, the dragon was always aware of our coming once we got close to it. Dragons become a lot more fun once they have cast mage armor, greater invisibility and shield on themselves.

If you are willing to Gate in 4 Solars to defeat the steel dragon, first I would say blowing that much XP and all the caster's highest level spells already constitutes using more the 25% of the party's resources, second no guarentee even that will defeat it. Sending Solars after an innocent creatures is a good way to get celestial payback too.

I can tell you from personal experience that there is a very significant change from 18 to 20. You are only looking at it in regards to caster level, but I can tell you that other things start clicking around that level. A shifter for instance suddenly becomes very, very dangerous as he gains access to things like a Bone Ooze and the Pit Fiend. People tend to finish off the top levels of prestige classes in those levels and gain the most powerful abilities.