An episode idea: Frustrating Enemies.
In the poll about 'turn off's in roguelikes Legend brought up what I think he called 'cheap enemies.'
Level Draining Wights in many games, The freakin' Ants in Rodney that suck down my strength, Rust Monsters and Legend mentioned the Egg Plant Wizards from Kid Icarus.
The original Rogue was full of these cringe worthy guys, including
-Giant Ant hits you lose one point of strength, works off of poison resistance.
-Floating Eye paralyze only. No attack.
-Invisible Stalker is invisible.
-Leprechaun steals some of your gold and promptly vanishes.
-Mimic can imitate objects, including stairways.
-Nymph steals something valuable and promptly vanishes.
-Rust Monster corrodes. No attack.
-Umber Hulk confuses you, save vs magic.
-Vampire bites reduce your maximum hit points.
-Wraith can inflict poisoned wounds that reduce your level of wizardry and your maximum hit points.
I really like that sort of thing. An otherwise weakish enemy with a dynamite special ability. Not an insta-kill, but one that strikes fear. One little mistake and BAM. You don't have to restart, but you might want to.