Least favorite tile/element/monster?

[quiznos00]

And my least favorite thing will probably be the teleporter. Despite its incredibly huge potential for anything, people have reversed its original uses to trick players and create artificially hard puzzles, just by the sole fact that you don't have a single clue what you have to do until you've tried everything at hand

The same could be said for blocks, too

I also don't like anymore the fact that you have for the most part absolutely no idea what's on the other side and you must be prepared to react to evilness (cue Telenet, Drawn and Quartered, Oversea Delivery, Alphabet Soup, Tele-Rooms, etc.)

Except for Oversea Delivery, which I used to hate a lot more when I was younger except I've now realized it isn't bad.

And I feel even though teleports have the potential for abusing the player, they aren't abused that much.