New Redemption Grab Bag now includes an assortment of 500 cards from five (5) different expansion sets. Available at Cactus website.
One of my favorite cards is the silly Jack of All Trades, which lets you gain a silver, spy the top card of your deck, draw up to 5, and trash a non-treasure.
Oh, and Trader is absurd and awesome! (Trash a card, gain a number of silvers equal to its cost. As a reaction, whenever you would gain a card, you can gain a Silver instead.)
I'm not sure why Tunnel is OP - if anything, it's a great counter to cards like Militia, Ghost Ship, Pirate Ship, Tribute, etc, which are all powerful attack cards.
Our test games saw a lot more action with Mandarin than most other cards, especially when combined with Royal Seal.
(By the way, Tribute is not technically an attack.)