First of get your Atlas completion higher. Do all maps to t15. Leave only Elder Tower as t16.
Chisel all maps to 20q, roll them high quantity +80, use vaal orb, use 4 sextants (only good ones with extra mobs), use 3 x different sac fragments and zana beyond mod. Thats how I sustain any t16, very expensive! I really suggest to run some white sextant Area map, those are much cheaper.