Undead. All cards with icon bonuses played against Winslow lose 2 levels because of his freezing cold touch.
Copyrights:
TSR
Wizards of the Coast
From the endless hordes of really good undead champions comes Winslow, with his high level and great battle power.
Note that this card reads icon bonuses. A card in most cases has to have a plus sign in the card icon for Winslow to drain two levels and champions don't have the plus sign. The exception to this is when a champion borrows another champion to use as an ally in battle. When something is used as an ally, it has an invisible plus sign before the icon number. For example, you are facing Winslow in battle with a champion who wears the Helmet of Selnor (33/UD) which allows you borrow Helm (255/4th) from a pool. Helm is now a level 6 ally who then loses 2 levels to Winslow to become a level 4 ally.
Combine Winslow's power with that of Negative Planar Energy (73/NS) and watch the opposing champion's adjusted level really drop. Winslow also works well in a deck using the dungeon card Spells from the Grave (19/DU), giving a combat option to an otherwise spell heavy deck.