well, with redlibra on spend 3-4 billion to try both classes (use chaos essence not stone so you retain common skills since both are Tyr)
your question is incredibly difficult to answer. I have a dualclass dread on my DK, 116, he can single spot ios just fine with a simple bloody r110 spear. TOI is difficult even on lower levels but IDC cause I do TOI /Ateliaon my main. Same for dethrone. But has +15 cloak, top ruby/redcat, greater rest jewels, +10 main artifacts +4 or +7 lessers etc.