Tally by LibraryAdventurer
Dunno if this was intended, but the strategy here is to use it every turn and keep your coppers out of your deck. If you open with a +Buy card on turn 1, you can do this every turn beginning on turn 2 and build extremely quickly from there. I think it's stronger than chapel, and maybe beats donate on some boards because you keep your buying power while simultaneously thinning. It's kinda cool for that reason and I'd love to play a few games with it, but I can't select it for being so powerful. P.S. I did the math and this+travelling fair alone drains provinces in 9 turns while also buying a duchy and estate.
Wow, really? (not sarcastic)
We've used this several times and always treated as a consolation buy when we ended up with only 2 or 3 coin with nothing worth buying at that cost, or later with an extra buy and a few coins left over after half my coppers are trashed (which is exactly what it's meant for). I actually find it hard to believe it can empty provinces in 9 turns with Travelling Fair. Maybe it'd work better if it said "up to 3 coppers"?
T1: play some coppers, buy Tally
T2: play 7 coppers, buy 2x Travelling Fair, Tally, 2x Copper.
T3: play 9 coppers, buy 3x Travelling Fair, Tally, 3x Copper.
T4: play 12 coppers, buy 5x Travelling Fair, Tally, 5x Copper.
T5: play 17 coppers, buy 3x Travelling Fair, Tally, Province, 2x Copper.
T6: play 19 coppers, buy 4x Travelling Fair, Tally, Province, 3x Copper.
T7: play 22 coppers, buy 6x Travelling Fair, Tally, Province, 5x Copper.
T8: play 27 coppers, buy 4x Travelling Fair, Tally, 2x Province, 2x Copper.
T9: play 29 coppers, buy 2x Travelling Fair, 3x Province.
If you have 4 or 5 T1 and get lucky with your T2 hand (ie have an Estate on the bottom of your deck) then you can buy an extra Copper T1 and an extra Copper T2, and you get the Duchy and Estate pubby mentions.