While Rhys is vulnerable at 1/1, and his ability is quite expensive, his low mana cost makes him easy to weave into a turn, forcing your opponents to answer him immediately or else
The Crimson Storm attack requires players to discard 2x Fire Energies in exchange for dealing 200 damage in a single turn, which is already powerful but can take a few turns to set up
Cutting Haunter is something I have done before, but it is really risky to do in a tournament environment since I can no longer set up Gengar under Trainer lock
Norman Osborn / Green Goblin By itself, Norman Osborn is a 1/1 unblockable creature that connives, which means it gets stronger as time goes by, while discarding key cards to use later
For four-mana, you drain one of your opponents of two life, and then you gain two life
Frequently, it isn't obvious how Jund's winning each exchange, because the trades are one-for-ones