Random synergy can be a great thing.
Last night, for index card D&D, I created a mech pilot character class whose starting item was a mech. Now, the mech was OP as hell, had ridiculous attack powers and was really hard to destroy. The catch, however, was that being a mech, it could only fit down certain corridors. It pretty much had to be abandoned in the first room of the dungeon. One of the other random items I’d made up for the dungeon deck was a 20 ft. Vibro-blade. It did 4d6+8 damage, except it could only be used by giants, high-level ogres, and mechs; it specifically counted as a “useless item” (certain classes benefited from acquisition or destruction of said useless items) if no one was present who could use it. It was a joke item that couldn’t really be used. Except it was used.
One of the players had written up an item of “Eat Me” Cookies that would triple your size. I found them. Of course the catch was that, much like the mech, you couldn’t leave the room you were in because you were too big and you could only shrink by crying or using the “Drink Me” Potion (which got smashed when it was dropped when people were trying to get the roaches from the Cardboard Garden brushed off of them). But being tripled in size would clearly fulfill the “giant” criteria.
We were experimenting with new boss rules this time, and had a path that specifically led to a “Boss” that was on the other side of a crocodile filled moat. So, we had the whole party carry the 20 ft Vibro-blade, used it to bridge the moat, pulled it across behind us, I ate the cookies and used it to fight the Ogre King, a 15’ tall 70HP badass. I nat 20ed him, and knocked him down almost 50 points.
Except, awesome as that was, in the end, what really did him in was a spell I’d written that someone else had found and cast, Derrik’s Daring Dweomer. It was a high casting cost spell that would either severely hurt the caster, turn enemies into metal, turn enemies into kittens, cause the magic user to explode and do stupid amounts of damage to all enemies (20 dmg for 100), or a couple other weird things. It turned the Ogre King into a 1hp kitten that I had to smash with the Vibro-blade so that I could cry and return to my normal size.