I am become death, the destroyer of worlds. -J. Robert Oppenheimer
Masquerade? Discard attacks? Don't need them. What if I told you there exists a pin which requires you to increase your opponent's hand size? Crazy? Perhaps. True? Absolutely. Practical? Probably not.
The key cards are Possession, Forge, and Governor/Council room. A King's Court won't hurt either. Can you find it? Spoilers for those who want to try on their own.
The pin works by a quirky little rule interaction (HT: greatexpectations for pointing it out to me). A new 5 card hand is drawn during the clean-up phase. Cards trashed while possessed don't return until after your turn, AFTER you've drawn your 5 card hand. See it now? The idea is simple. Have your opponent draw his entire deck with Governor/Council room (that's where KC comes in handy). One of his cards has to be a Forge. Play possession. Forge away his entire deck. During his possessed clean up phase, he can only draw Forge. That's the only card in his deck. Only after clean-up is the rest of his deck returned to him. At best he can gain 2 Coppers.
And now next time you see a board of KC, Governor, Forge, Possession you will be ready to destroy someone's world.