Also, I'm remaking one of my mono Black decks into a discard deck. So far I have:
2x
Megrim
2x
Duress
2x
Bloodhusk Ritualist
1x
Fugue
1x
Coercion
1x
The Rack
1x
Geth's Grimoire
1x
Guiltfeeder
Any ideas?
Definitely some hypnotic specters.
liliana's caress instead of megrims. Cheaper but does the same thing.
And of course Hymn to Tourach and Inquisition of kozilek, no discard deck is complete without them.
If you can afford it get at least one Lilana of the veil in there.
If you have some dual lands, splash red for blightning. Hellhole rats are an interesting option as well.
Cry of contrition is fairly nice but not a must have.
You might want to consider at least one delirium skeins. It does make you discard 3 cards as well, but if you have a curse or megrim out, that's 6 damage that can end the game for you.
Despise is a great discard card imo.
Dimir cutpurse is a decent three drop creature
Distress is another decent discard card
You might want to try some dream salvages, which will let you draw cards (this one is iffy, I'm just curious if they'd be useful or not)
Some funeral charms are another option
Scepter of Fugue lets you make an opponent discard repeatedly.
If you are rolling in case get some copies of thoughtseize
Unmask will give you an extra discard spell first turn provided you are willing to discard a card for it.
Also remember to have a way to win if discard doesn't pan out (which it very often doesn't). You'll want a plan B so to speak. Most good discard decks I've seen don't make discard the primary means of attack, it's a way to thin out an opponents hand first turn or two and then you drop your own creatures. Tombstalkers might be a good option.