How much shadow resistance blood princes ranged tank?

ok i got a few questions, im being shoved into being the ranged tank for guilds ICC tonight and need to know a few things about it, im a mage also to make it even more complicated the guilds only warlock just /gquit... so im in here for core team as our main dps on the rest of fights and tanking for princes. i made an OS for this as arcane for a few differant reasons im uming armor still applies to these fights so as of now i have 21.6% damage reduction (including talents) that increase armor = 150% of my intellect so i have 4k armor, i can make 4k armor potions for when it gets bad also if armor does still apply. i also have 140 shadow resistance from magic absorbation talent and the improved mage armor talent. mage armor just gives restances and faster mana regen so i can put on mana shield which will drain mana instead of health and im uming if i keep mana up ill be able to stay alive. i got head sholders gloves and legs to gem / enchant (old 245s) and advice for gems and enchants (probably shadow resistance?) extremly lost and need to pull this also together by tonight