Question: How to derail a sandbox campaign? This is my first campaign. In this campaign, I am a level 9 high elf circle of the mood druid, and my DM challenged me to derail the campaign. More like said "if you have an idea to derail the campaign, give it your best shot. (I should mention that this is a high magic campaign) They do approve homebrew items (After they balance them of course) and has actually put a few homebrew magic items I have made into the campaign. I already have a master plan to become an ancient brass dragon through the use of two homebrew items they liked and approved. An orb that has the ability to cast true polymorph (It has a 2d10 day recharge) and can cast the polymorph spell once a day. And a scroll that temporarily raises your challenge rating to 20. (Said scroll has a week long recharge and a CR 20 creature spawns within 10 miles and hunts you down... so that CR boost better be worth it) But I think you see where this is going. CR 20 + True polymorph = Dragon forever.

My party: Me: Person who is smart enough to not kill somebody in a town owned by a dragon, High elf circle of the moon druid.
Murderhobo Warforged oathbreaker paladin
Cat kicking Aasimar cleric
Recently turned Murderhobo Goliath champion fighter

Things that could help derailing: I have the rod of rulership... Very stronk.
"Orb of air bubble" It's exactly what it sounds like.
About 18 cats that are better at chess than most people.
A backpack that we should get soon that literally poops out 10 platinum every time someone says platinum.
An "Arch siren" stuck in a crystal that we know the location to.
A literal demon that vandalized our house.
A fey Death Cult that we are working for. (TOTALLY the good guys)
An undead super-powered npc maybe bard "Friend"
The awaken spell.

I think that's all!

Isn't a sandbox campaign one in which you can do anything?

Thus, perhaps, the only way to derail it is to do nothing?

huh

1. We need context. What's the story/campaign arc that you are attempting to derail?

2. It doesn't matter how clever you are or how much shit you make up. If the DM doesn't want you to derail the campaign via your methods, it won't ever happen. 

Example: Seeing as much of what you typed is crazy sauce made-up, have fun with it sort of stuff, here goes:

At dawn each day, all trees in the world shed their bark, bursting forth with arcane energy. Ley lines form and begin to zigzag across the world, like a massive 'Mission Impossible' laser alarm system that even the most dexterous can't bypass. After a minute, the ley energy is so abundant that in a 600ft. radius (wherever the DM decides), all brass dragons are locked in stasis and all magic items not originating from the 'world trees' cease to function. In addition, all stats are reduced to the result on a 1d6 roll. This worldwide effect ends after 1d4 hours..

Yeah, like Farling stated, the point of a sandbox is that it can’t be derailed. But... if I really wanted to try... open a haberdashers shop or a confection shop.

Quote from Farling >>

Isn't a sandbox campaign one in which you can do anything?

Thus, perhaps, the only way to derail it is to do nothing?

 A STRANGE GAME.

THE ONLY WINNING MOVE IS NOT TO PLAY.

I agree with the others. One cannot derail a sandbox campaign. 

It almost sounds like the DM thinks they have a fool-proof iron-clad plot that no player could possibly derail and wants to see if anyone can. That's not a sandbox.

Whittle some dice, get some parchment to write on, have everyone in the party start creating characters to play in the campaign your character is running.