Also, any card with "otherwise" lets you flip the outcomes, and is almost always broken, including Menagerie (the card, not the expansion), Jester (gain a Province, give Curses instead of gaining/giving Silver, etc.), Giant (always hit the attack), and Leprechaun (gain a Gold + a Wish every time).
EDIT: Jester not that great, as you'd have to decide to flip it before you see what's discarded.