okay if I'm fighting a wall of skellies and say for some odd reason I have 4 attacks 3 from just being a skink chief and the 4th from wielding a second close combat weapon. and also let's say I wound 4 skellies and all 4 fail their save. does that mean 8 skellies die? do the extra wounds from pirahna blade go into the rest of the unit is what I'm asking I guess.
Nope only 4 skeletons would die in that situation, the pirahna blade deals 2 wounds to creatures that have multiple wounds such as ogres, monsters, heroes chariots ect.
One thing I have always wondered, do the double wounds count towards CR? evven if they are single wound targets?
Slightly aside from your question but i thought it worth mentioning... If you had 3 attacks, an extra hand weapon and a Piranha Blade you would not have 4 attacks when using the Piranha Blade, you would only have 3. Magical weapons can not be used in conjunction with any other weapons (standard or magical). You could have 4 attacks (normal) or 3 attacks that split into 2 wounds after saves thanks to the Piranha Blade.
I am not sure where it says in the rulebook but I would assume that it would only count in a challenge as overkill or on non characters as the actual wounds caused.
Yep, except if you take a magic weapon you have to use it. This stops people (aside from Bretonnians, who have a special rule for it) charging in with a lance then switching to a magic weapon in the next round of combat. I am pretty sure the extra wounds don't count towards combat res, since it is more the amount of wounds the lose (ie deaths or wounds off ogres etc) rather than what your magic weapon can do. In a challenge, they would count toward overkill though.
There are other weapons and magic items that add extra CR (eg the Laurels of victory which kurt helburg uses) However the weapon does not have the same little clause. It just causes two wounds against multi wound creatures Pg 31 of the LRB "Hits inflicting multiple wounds" "If the model only has 1 wound on its profile, there is no need to do this (rolling additional dice in the case of war machines), as models cannot suffer more wounds than on their profile. The victim dies instandly and any excess wounds are wasted." This is the rule for shooting and i assume that it applies for CC
on that same thought say you were fighting an ogre bull unit and had 4 wounds which then became 8 how would that work out would you have to roll seperatly for each attack and work it out that way or kill 2 1/2 ogres since they have multiple wounds
That is where it becomes difficult... If you hit and wounded 4 times, technically you would have 4 ogres with one wound left. If there were only 3 in the unit, 2 of the attacks (so 4 wounds) could be allocated to one ogre and kill him, leaving the other two wounded twice. It becomes pretty trick to keep track of that though.
I don't think thats how it works. Of course I dont think there are rules to make any way 100% certain. As a character you choose what you want to attack with each attack you have. The rule book says that characters can distribute attacks between any character they are in base contact with or any unit they are in base contact with. In this case I am assuming that the character decides to attack the unit of Ogre Bulls. Example Against the Ogre Bulls with Piranha Blade 4 Attacks. 4 Hits. 4 Wounds. 0 Saves. +2 Wounds to one Bull Ogre from 1 Hit (+1 from Piranha Blade). +1 Wound to the same Bull Ogre (-1 wasted from Piranha Blade). Bull Ogre dies +2 Wounds to one Bull Ogre from 1 Hit (+1 from Piranha Blade). +1 Wound to the same Bull Ogre (-1 wasted from Piranha Blade). Bull Ogre dies. 2 Dead Bull Ogres. 6 wounds inflicted. 6 Combat Res from Piranha Blade wounds.
This was recently covered in an FAQ, but multi wounds do count toward overkill. So 3 wounds from the piranha blade would turn into 6 CR (1 wound plus 5 overkill) in a challenge. On the same topic, killing blow against a W3 target gives you the full credit for 3 wounds. So one KB wound could generate 2 to 3 CR depending on your target's wounds. The question they haven't answered is can you get credit for multiple KB against a target in a challenge? My common sense answer is no, you can KB him once and just treat the rest of your hits as normal wounds to count toward overkill. I would imagine the blade of realities works the same way, but who knows!