May be cast at any time to counter any just played unarmed combat card, and makes the champion immune to unarmed combat cards for the duration of that combat round.
Copyrights:
TSR
Wizards of the Coast
While this is the only wizard spell that protects specifically against unarmed combat cards, it isn't that powerful.
Currently, 3 cards exist that negate a UCC: Reversal (435/4th), Counter (437/4th), and Evade (98/DR). All of these are usable by any champion, which by itself can make them more useful. Stoneskin's biggest advantage over these cards is that it protects you from any further UCCs for the round of battle.
This could be useful for a spell deck (with Mulmaster (33/1st) to let you draw a card from this counter), but not in most tournaments. Typically, the only UCCs people see in tournaments, specifically 55-card environments, are Slap! (78/IQ), Fighting Dirty! (3/DU-chase), and SOMETIMES Breath Weapon III (96/DR).
Very rarely in a tournament would you see more than one of these used in a combat round, therefore making Reversal the card of choice. The times to use this card is in more fun settings where dragon, undead, and hero decks show up more often. In those cases, this card will see more use and be most effective.