How are you supposed to fight a discard deck?
Against decks that rely on 3-8 precision cards to disrupt you but mostly consist of another strategy, I recommend these resources:


B&amp;CG: How can I play around targeted discard? — general advice
Reid Duke: Thoughtseize You — to understand what your opponent is
doing




Against decks that are practically wall-to-wall discard, here are some techniques that may help:

Get "under" them

Play out your hand faster than they can rip it apart. This is what your red aggro deck is doing.

Rely on strong topdecks

One of the biggest weaknesses of discard decks: most discard cards are sorcery speed. Even once you're "hellbent," you'll usually be able to draw your card and play it on your turn. So you'll still be making land drops and you'll be able to cast most of the permanents and removal spells in your deck.

The worst thing about playing a dedicated discard deck is that half the cards in your deck just do nothing once your opponent is topdecking. So, focus your resources on taking out the cards of their that still have value — finishers, combo pieces, and engines of advantage.

Play out of your graveyard

With some exceptions, discard typically puts stuff in your graveyard. Flashback spells, reanimation effects, self-reanimators (like Gravecrawler).

Incidental Hosers

Some staple creatures are also, incidentally, discard hosers — for example, Wilt-Leaf Liege, Loxodon Smiter, and Obstinate Baloth.

Precision tools

This is a quality sideboard card:



You can drop it on turn zero, for free. It blocks all of Thoughtseize, Cabal Therapy, Inquisition of Kozilek, Duress, and Hymn to Tourach. It's also a strong card against burn decks, many combo decks (e.g. Tendrils).