That means your opponent has to spend two spells if they want to do something, one removal spell to blow up the Barricade and then whatever their intended spell is
We've yet to add this commander to our cEDH tier list, but that's on us - she can take you all the way to the very top of the format
Doctor's companion (You can have two commanders if the other is the Doctor.) The first ability of Bill Potts will trigger as long as it is the only target of that spell or ability, even if that spell or ability could target multiple permanents
You might donate junk like Clues or Foods, harmless creatures, or even cursed permanents just to keep your draw engine flowing
Id rather have [casthaven]Thoughtseize[/casthaven], for any number of reasons, but [casthaven]Brain Maggot[/casthaven] offers a powerful discard effect as well
In other words, we're trying to make big illusions and then sacrifice them for even bigger payoffs