I was curious if you all found certain monsters to be exceptionally hard or easy for their difficulty?

For me 3 comes to mind:

1) Darklings: I find even medium threat darklings to be a joke to fight. Their attack is so low that once i have just a little bit of defense i can mow through them.

2) Ophidian: With a x3 special attack bite, very high defense, and magic immunity, i find these critters very tough for their normal medium threat. If i'm not careful with them i can get a tpk.

3) Trolls (any big creature with maul): These guys are a crapshoot. Sometimes i roll over them. Others then will butcher my strongest guys with a single maul. In other words, their threat level depends on the luck of the maul.