Playing Heroica we set up a board where the beginning branched to one way to a long hall of high level monsters and keyed doors, and to the other way with keys and potions. The plan was that they'd go gather the keys and stuff, then go face the boss but my most driven son decided to forego the loot gathering and charge straight for the boss, relying on perfect rolls to get through the doors and beat the monsters, and darned if he didn't claim victory before the rest of us gathered half the things. So we decided we needed a new mechanic. A door to stop people from charging the boss. The key eventually became a switch, and I give you the Lego Heroica Boss Door.