Hey there.

Recently theorycrafted around the endless delve unique blood of summer, first I came up with elemental Hit but that didnt look as promising.

This time around, I chose Spectral Helix for its immense scaling with flat damage.

https://pastebin.com/0eStyYPg

Main Idea is to use Ice Bite+9 Frenzy for flat Ele scaling, then stack evasion on gear and convert to armour for Big Molten Shell+Phys Mitigation. For Ele Mitigation, 76% max res and 100% spell suppression should work out rather nicely.

This is not a build for Aul or other bosses, but I am confident that one could delve well past level90 with this setup.

From my limited testing with a couple of scarabs in Scourge league, fossil supply should allow you to hit a similar chest eventually.

In the midgame, purity of elements can surely be used while working on gear with good resistance suffixes (Essences now drop in large quantities in Delve, that should facilitate this).

Maybe this can be improved further, personally I think this will be enough for me since I plan on going for a quick level 90 and then focus on the other events.