You can use Kanai's Cube to Extract Legendary Power:The first time an elite pack damages you, gain an absorb shield equal to 150% of your maximum Life for 10 seconds.
1.You need to provide your account.
2.After get St. Archew's Gage, we can help extract its' Legendary Power successfully by using Kanai's Cube.
3.ETA:1-2 days.