A little note on highway forge:
unless you're hogging all the highways, it's a bad idea:
if you trash n cards originally costing x_1, ..., x_n, and you've played m highways, then forge gives you a card originally costing
x_1 + x_2 + ... + x_n - nm + m. Since nm > m when n > 1 and m > 0, this is never as costly a card as you would get without having played any highways, and it's strictly a worse card if you're using forge well (i.e. trashing more than one card).
A particularly bad case of the formula is when m is 2. Then if you forge 3 estates and a copper, you gain an estate instead of a gold.
HOWEVER, there's an exception to this formula stemming from the fact that highway never reduces a cost below 0. If you play more highways than the minimum value of the x_i, it becomes possible that the highways improve your forging. It's annoying to write out the formula, but it's obvious that good stuff can happen here when you consider the extreme example where you've played 8 highways and can forge anything into a province.