Okay, just played a first playtest game with the following version of Treacherous Tonic:
1P
+2 cards
+P
Trash a card at random from your hand.
2 VP
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Kingdom:
Coin of the Realm, Raze, Scrying Pool, Alchemist, Dungeon, Guide, Golem, Artificer, Bridge Troll
Events: Alms, Lost Arts
Suffice it to say that the Tonic was terrible in the kingdom. This was a 3-player game, and one of the players (not me!) went very deep on tonics, which lead to a hilarious role-play that fit the card perfectly. However, I played Alchemist-Scrying Pool with my Lost Arts token on Alchemist, and played 8 Bridge Trolls to buy 9 Provinces one turn, and clean up the remaining 2 (1 to the non-tonic player) and a bunch of Duchies the following turn.
Going to try it out in more of a sloggy kingdom, where it might actually be a reasonable pickup.
EDIT:
Kingdom:
Pawn, Smugglers, Familiar, Treacherous Tonic, Militia, Nomad Camp, Cultist, Explorer, Rabble, Relic
Unsurprisingly, the Tonic was reasonable in this game. I only picked up one copy, as I got pretty lucky, always hitting my potion with enough cash to pick up familiar. After the curses ran low, I picked up a tonic. One of the other players picked up a couple and hit some junk out of his deck, but my accelerated junking carried the day. If the third player hadn't randomly piled on the Pawns, the Tonics would have been pretty good buys for a while.