It basically enter red portal to and from to refresh items in Anya Shop.
Things to buy include
Shops all Claws +4 Skills and up:
+1 Sin / +3 LS
+2 Sin / +3 LS
+2 Sin / +2 LS
+3 Traps / +3 LS
+2 Traps / + 2 LS
+1 Traps / +3 LS
+1 Sin / +3 WoF
+2 Sin / +3 WoF
+2 Sin / +2 WoF
+3 Traps / +3 WoF
+2 Traps / + 2 WoF
+1 Traps / +3 WoF
+1 Sin / +3 BS
+2 Sin / +3 BS
+2 Sin / +2 BS
+3 Traps / +3 BS
+2 Traps / + 2 BS
+1 Traps / +3 BS
+6 Shadow Master Claws
+6 Venom Claws
+6 Fade Claws
3/20 Jav / IaS Gloves
Jeweler's Armor of the Whale (4 soc / 100 life)
Artisan's Troll nest of deflecting (3 soc with deflecting mod)
And more