lf you activate the Rune Spirit Parasite in the Magic phase to receive +2 bonus to your Magic combat roll, it says you inflict +1 wound, does this wound take effect when you are defending .

Also can you even activate the Rune while defending.

I'm not 100% certain about this, but I seem to recall reading something somewhere in the rules/FAQ that bonuses to damage only apply if you have a chance of dealing damage in the first place (ie: you are attacking that phase.) That's what my gut tells me, but obviously we should wait for a more official answer.

Yes, if, in a phase, you are defending, you are not dealing damage so you can't use the rune. But that is if you are attacking (resolving a challenge or attacking other player), if you are being attacked by another player (you are effectively a challenge) then you can use the rune (all items, but no allies) in any phase (this is described in here : http://new.fantasyflightgames.com/edge_news.asp?eidn=105 ).

The link did not work for me.

http://new.fantasyflightgames.com/edge_news.asp?eidn=105

again, but that one works ok to me.

Anyway,here is where you can find it : on the game page (catalog->board games -> RB) under support to the bottom of the page under references first line says "A detailed description of the player versus player combat featuring Mordrog and Mad Carthos!" and part of it is a link