Lord Pendragon said:
There is some debate on this question, I believe.
Yeah - the flavour text notes "some of its wounds are transferred to you". Some interpret this so that if the wound is of a sort that would not normally affect you, it can't affect you.
Likewise, "The amount of damage not taken by the warded creature is taken by you" has room for interpretation. 'He didn't take 5 points of fire damage' , therefore 'you take 5 points of fire damage'... which would be protected against by Fire Resistance.
The other point of debate is what happens if a Shielding creature has regeneration. Do the 11 points of slashing damage you take as a result of the 21 point greataxe attack on your partner deal lethal damage to you, or does your regeneration convert them to non-lethal damage?
My personal reading is in line with Lord Pendragon's - you take the damage, with no way of protecting against it. But it's debated.
(It's also interesting to see what happens when two people shield
each other. If the redirected damage counts as an 'attack dealt by a special ability', then it gets bounced back and forth...
Person A gets hit for 33 points; he takes 16 damage, and 17 are redirected to B.
B takes 8 points, 9 are redirected back to A.
A takes 4 points, 5 are redirected back to B.
B takes 2 points, 1 is redirected back to A.
Here's where we have a problem. A takes no damage, and 1 point bounces back to B... who takes no damage, and the point bounces back to A again.
Can't really determine what happens to that point, though if Spell Turning is anything to judge by, there's a chance of opening a rift to another plane...

)
-Hyp.