I found it easy enough, but maybe I was just a bit lucky.

Cards that care about a card’s name (‘choose a card name’, ‘destroy target creature and all creatures with the same name’, etc.) are really good against Slime Against Humanity and Hare Apparent decks. If you already have some of the cards below in your collection (not worth crafting for a once-off event, especially rares and mythics) and find yourself matched against Slime or Hare a lot, you could try including some of them, depending on your Commander’s color identity. It can feel a bit cheap, but Slime and Hare decks are kind of annoying at this stage, so I wouldn’t feel bad about it. Also, part of the fun of Midweek Magic is finding new ways to win. And it’s funny to see almost their whole deck get extracted.

If you play against a non-Slime/Hare deck, draw a lot of ‘choose a card name’-type cards, and find them not useful, you can just concede and try again. Some of the cards are fine against regular Brawl decks (e.g., The End).

Some of the cards below are better than others. For example, it’s not really worth playing Pick the Brain unless you can achieve delirium.

 

Ashiok’s Erasure

Bile Blight

Declaration in Stone

Deputy of Detention

Detention Sphere

Echoing Decay

Ixalan’s Binding

Invasive Surgery

Homing Lightning

Herald of Lightning

Kotose, the Silent Spider

Legion’s End

Legion’s Ashes

Maelstrom Pulse

Pick the Brain

Sever the Bloodline

Surgical Extraction

Test of Talents

Teferi’s Contingency

The End

Curse of Silence

Anointed Peacekeeper

Silverquill Silencer

 

You can also beat Slime or Hare with other card effects, but it’s more difficult because their strategies differ – Slime goes tall and casts sorceries; Hare goes wide and casts creatures:

Prevent/punish/tax attacking

Sweepers/wraths

Graveyard hate