One of the things I have discovered since I picked up PvP is the difference in deck set up. PvP can take anywhere from mere minutes to several hours per match. It all depends upon the skill level and luck potential of all the wizards participating ;)
My life wizard's deck is MUCH different for farming than it is for PvP. In farming (or questing for that matter) I like to have as few cards as possible in my hand. That way I can draw the card I want and/or NEED when it's useful, not 3 turns later! I basically run around with blades, gargantuan, Chewies (Forest Lord) and a few heals. I don't even bother to carry shields any more unless I am with a group of lower level wizards or the farm we are doing can be difficult.
Now my Pyro will carry some shields as she isn't quite the tank that Life wiz is! But again it all depends on what I am doing. I usually just carry blades, gargantuan and some meteors. Having a AoE that can hit for 900 health at four pips is pretty darn nice and if it goes critical BAM! dead mobs :D I was farming Calypso the other day with Kevin SoulStalker, a fellow Merc, and hit a crit meteor that did over 5k damage -- talk about POWER! lol
My death wizard runs around with empowers, blades and crows. If she is going against balance mobs or life mobs will pack some poisons for those pesky shields! Again my death wiz is pretty much a tank and doesn't pack shields unless I am with other wizards, after all she can steal back health ;)
Now my balance wizard's deck can vary the most. Again, depends on who I am with or what I am doing. I don't really even pack Lady Judgement anymore, blades and Aoe all the way! If I am with elemental schools, or spirit schools I will pack blades for them to play with too. I do love my Spectral Blasts and will use them the most it seems.
Now onto PvP deck setup, at least for me ... I play very defensively on all my wizards when in PvP. I will max out all the shields I can in my deck across all wizards. If I don't use them I can always place them on a teammate or discard them. I find that I prefer a large deck -- scratch that -- HUGE deck in PvP. I know many will not agree with me BUT its my opinion and I'm sticking to it! Since I have been doing mostly 4v4 lately I find myself being even MORE defensive. If I can reduce the damage that I or my teammates take that means I can conserve my pips and heal less often. The faster your team can build pips, the quicker you can dish out damage, the quicker you dish out damage the more likely you are to spike the other teams health and win!
I don't pack many hits, my job as a life wizard is to keep my team ALIVE. I can't do that if I have wasted my pips on a hit that my teammates are better able to accomplish. With that being said there are times that I do get to make the final blow as my team has spiked our opponents health and we need a killing AoE to finish them off. Some days the cards fall into place, and some days they don't ;)