There are three sets of probabilities, if you are below level 12, 12 to 90 and above 90. I will ignore the first one for simplicity
Dread Skull 3.52%
Symbol of Solael 2.35%
Ancient Armorplate 4.69%
Mark of the Myrmidon 4.69%
Lodestone 2.35%
Spellwoven Treads 4.69%
Unholy Inscription 4.69%
Arcane Lens 2.35%
Bindings of Bysmiel 4.69%
Chains of Oleron 4.69%
Hallowed Ground 4.69%
Devil-touched Ammo 3.52%
Mark of Dreeg 3.52%
First % up to level 90, second % level 90 and up:
Ancient Heart 13.05%, 4.65%
Blood of Ch’thon 12.31%, 4.65%
Tainted Brain 12.80%, 4.65%
Manticore Eye 1.97%, 1.86%
Skeleton Key 0.49%, 0.46%
Aetherial Missive 2.46%, 9.30%
Aetherial Mutagen 2.46%, 9.30%
Ugdenbloom 1.23%, 2.32%
Wendigo Spirit 2.46%, 9.30%
Celestial Lotus 0.25%, 1.16%
Eldritch Essence 0.49%, 2.32%
Both sets have a 50% total each, if this does not add up, these are rounding errors 