I want to make a deck that just messes with people's decks. I play casual multiplayer 99% of the time so I'm looking for cards that can mess with many people at a time. It doesn't need to be a winning deck, just something to screw with everyone's deck.
Some cards ideas I have already are: {Confusion in the Ranks} and {Possibility Storm}
{Descent into Madness}
There was this really fun mono black creatureless deck I used to play ill see if I can dig up a deck list, it was tons of sac effects and weird interactions.
{stolen goods},{commandeer},{switcheroo},{conjured currancy} all come to mind.
If you play casual try {Letter Bomb}, I wish they'd make black boarder cards like this, but it would be difficult to enforce.
{Naked Singularity}, that blue enchantment that has a similar effect, {Scrambleverse}
(Recommend flickers to keep the cumulative upkeep low)
Check out my "total madness" deck in the commander section. It's 100 cards of chaos, and super fun. It should still be on page 1 or 2. You should find lots of chaotic cards to your liking in that decklist :)
How about {Hive Mind}?
{Descent into Madness} + {Assemble the Legion} = win
Fun weird card {shared fate}
Most cards from the Unhinged block.
Well for mutual benefit, you have cards like {Omen Machine} and {Wild Evocation}.
For mutual confusion, you have {Elkin Lair} and {Warp World}.
BUT, if you really want some crazy stuff, there's the silver bordered {Free-for-All} and {Camouflage}, guaranteed to stop the game for at least five minutes while everyone reads the card.
And {Curse of Exhaustion} for a targeted lockout