What are the toughest encounters for each CR ?

[awaken_D_M_golem]

... Ephemeral Swarm

CR 5
hmm would a Cleric tagging that with 1 Turning attempt
be able to knock off part of the Swarm on a per HD basis?

[zook1shoe]

There's lots of monsters that have weakness... I listed a monster that does, but is deadly if unprepared. So are golem and trolls w/o the right weapons

[deadkitten]

This could sorta turn into a fun project. Possibly starting with the lowest CR, creating a sort of ranking system within that range and then moving on to the next highest.

You can always find the most notable offenders by searching the internet and get stuff that is under CR, but there are probably some monsters that haven't gotten the attention they deserve cause there are huge outliers already present in that particular CR.

I know I would love an attempt at a comprehensive scaling system for monsters. I don't think it has really been done yet and Wizards kinda done a poor job of it themselves.

[awaken_D_M_golem]

I'll update the list (soon) but on the 1st post, you know, like as if I knew what the plan was ahead of time.
    

CR 6 or 7 could be a Duergar with 1 Caster level interaction and Leadership.
Wonder how LA Buy-off works with CR (uh-oh can of worms)?

Maybe need a standard of using 1 trick once and done.

A big list of monsters would be good, with as
many books as possible given the legalities.
Looks like Sinfire got interested in another thread.

[awaken_D_M_golem]

This reminds me of something.... oh yes. About six years ago this was born.

Slow, Pathetic, Magebred Toads with Shape Soulmeld: Dissolving Spittle and random Feat that gives a point of essentia.
10 of them is CR 1.
Nothing like the "Amphibian Paraplegic Assault Brigade" to ruin your day.

Noticed there were very few CR 1/6 things available.

Clearly any CR 1/10 or 1/8 could use similar tactics.
It's basically a Commoner Campaign dumpster dive,
for stuff that works with individually weak critters.
I like it.  Technically it's "earlier" than a 1hd gets going.

A decent sized batch like your 10 or smaller too,
can definitely give a Kobold MacGyver / MacGruber (?)
a run for it's money. 

I mean this is at the Housecat vs. Fighter level here.