First spotted by GamesRadar, user Kill-bray on the Baldur's Gate 3 subreddit discovered a deliciously convoluted way to punk Act 2 necromancer boss, Balthazar: smuggle an anti-magic flower that's never meant to leave the game's first act across fantasy state lines and slip it into the rude dude's pocket. We might not have the full-on Dispel Magic effect from tabletop D&D, but there are still ways to ruin a wizard's day.
The Sussur Bloom is the anti-magic flower in question. There are a few scattered around Act 1's Underdark zone, and they feature in the sick Arcane Tower side quest as a puzzle solution. The little buggers emit a field with the Silence spell effect, preventing spellcasting within a certain radius, and the blooms are supposed to disintegrate upon leaving the Underdark.
Just like with the Shadowboxing speedrun tech or disposing of late game plot-critical items and getting a weird game over for it, inventory containers like pouches or backpacks seem to bork Baldur's Gate 3's usual rules, and Kill-bray found that shoving a Sussur Bloom into one such vessel let them take the item out of the Underdark.
Kill-bray then kept that preserved bloom in reserve (presumably at camp and not permanently messing up spells on their person) for the first encounter with Balthazar, potentially dozens of hours after you first encounter Sussur Blooms and well into the game's second act. In Bethesda-style hot potato grenade reverse-pickpocket tradition, they slipped the bloom, still in its protective pouch, into Balthazar's inventory via the Sleight of Hand skill. Now that powerful wizard was stuck with a persistent spell-cancelling AoE localized on his person.
While it's possible to kill old Balth when you first meet him and be done with it, Kill-bray went the extra mile and waited for his proper climax fight at least a few more hours later (after making it through the particularly long dungeon, The Gauntlet of Shar). Because Baldur's Gate 3 uses persistent NPC data, as opposed to separate instances loaded for different encounters, Balthazar still had that anti-magic bloom in his pants. After delivering his big villain speech, he was stuck just running around until the party put him out of his misery.
It's yet another example of just how malleable Baldur's Gate 3 can be, even as you push past its every limit. Sussur Blooms were never meant to be taken out of their native habitat, and yet, brought to the farthest frontiers of Baldur's Gate 3, they still work exactly as intended.