I usually take similar gear, maybe little cheaper, and it works fine. When i enter the cave i barrage rex with dds equipped, spec supreme (usually dies in 3-4 specs), keep fcing rex, range prime, spec supreme again, rex, prime and so forth. I personally dont like killing rex just b4 prime to warn about prayer switch, as i can kill them b4 the other one spawns. I have 94rang/mage, 81str + piety, war tortoise and 80def If i can get 700k/h+ in there, im sure u can get alot more, and complete ur task =)
