Doug McCrae said:Dr Fear's cockatrice. The level 4 PCs heard rumours that this crime boss could turn his victims to stone and even found a statue. One PC was bitten twice by the albino's pet in the final battle but made the (easy) save both times. At this level there was really no defence or recourse if a PC had been stoned.
Fun. Seems fair. Easy saves are good because a) the player doesn't know how easy they are, so they are still scared, and b) even if they do know how easy they are, there's still that 5% chance looming over them. Do they feel luckY
A medusa assassin ambushed the PCs in retaliation for their operations against Daask. There was no warning whatsoever, just a hard spot check to see through the disguise. Three (out of four) had to save. The one who failed didn't get to take a single action. Stone to Flesh is a level 6 spell and hence unavailable in Eberron, though Stone Salve can be purchased. The group paid the 4000gp for it, but the PC failed his system shock and died. The player, understandably a bit hacked off, elected to make up a new PC at that point.
Old school. Awesome.
A (deceased) wizard's library, guarded by a logic puzzle. The wizard's programmed image warned of severe consequences for any mistakes. A floating black skull with a black gem in its forehead cast Finger of Death if the wrong answer was given. It fired once for a single error, and twice at the PC trying to prise the gem out (old skool!). All saves passed.
As long as there was an option to bypass or ignore it without stopping the whole adventure, I don't see a problem with this. Players making informed choices is always better than not.