This is what Rushes posted:
If you start a game of Raven and then leave your computer alone without touching either keyboard or mouse for about an hour or so, then the puzzle *should* auto-solve and the antidote will appear in your inventory.
However, several members have reported this skip feature not working for them. But it's worth a try.
Otherwise, keep starting a new game until you find one which has many more ravens than snakes and so will be likely easier to win. The ratios do vary from game to game.
See if that works for you.