A question for Donald X: Has there ever been any thought of creating cost increasers?
I tried searching the forum for prior discussions but couldn't find anything. We have Bridge, Highway, Bridge Troll, Quarry and Peddler, all of which are cost reducers, but there are no cards that I can think of that cause cards to cost more (Summon, Ball and Seaway, arguably, but that's a stretch.)
A cost-increasing attack seems plausible, though on reflection, it could be more painfully crippling than any other attack, particularly if it stacked. The fact that even the -1 coin token can't stack, and that there's no attack that gives debt is probably a good indication that this is a non-starter.