Actually, the topic was to talk about the game in the OP. But people have been using it to list a bunch of over-hard counters. Now, secret chamber sorta can be over-hard, in that you can mess with your shuffle/deck distribution, but... eh, not really.
HT is nice for attacks that don't actually do anything at some point, as mentioned.
Watchtower is over-hard to torturer.
Actually, I think HT to minion, Watchtower torturer, multiple HTs to any discard attack, and trader to ambassador/cursers are the only truly over-hard things, in that they stop the attack totally and give a benefit. The others are... over-soft? In that they can somtimes help out more than the attack hurts, but they don't stop the attacks effectiveness.