Starting to get better at bombtanking rokface boss. It's the only role I haven't done yet (@500kc). Once I feel comfortable with consistent 2 kill nihil trips w/o penance i'll be a happy camper.
Don't lure the spiders. You should be able to DPS araxxi fast enough! Also especially all four hurts you. You want those stalls during Araxxi. (Araxxi absorbs the silly deadly acid thingy message)
If you have Onslaught and can use it at 25k, get rid of 10 storm shards at the start to get Araxxi down to 80k~ and the first special is usually 50% acid and the second will either be a swipe or cocoon. You should be able to get Araxxi down to 50k in that time
I hate Onslaught for Araxxor, I prefer to just Berserk start of P4 and drop Araxxi down below 50k. By then she'll only spawn one wave of minions or absorb one helping of acid, then I finish off with Blood Tendrils right before 25k.