Some times I like to throw a little twist in there. Something in those odd times when success is actually failure and failure is actually success.
I know this sounds weird. The concept actually spawned in my brain a long time ago with Castles & Crusades. The C&C Illusionist is the coolest one I’ve seen. I haven’t kept up with additional printings, so I don’t know if there’s been any changes in the class. But in my old version, Illusionists got healing spells but there’s a catch. For them to work, the target has to FAIL as Save vs Magic.
Don’t use this idea too often or the weirdness wears off. Every time a character makes some sort check or Saving, they are assuming that the best outcome will be if they succeed on the roll.
This can be applied to the triggering of magical trap or item. Reading ancient runes or scripts. Or even crazy interaction with NPC’s.
Like I said, this isn’t something to be used too often. If everything is weird and topsy turvey then, nothing is. Just another little trick for a DM to keep in their back pocket if things get a little boring.