Arcane Anomalies are an extremely rare item containing a large variety of resources, obtained via the similarly-named Arcane Anomaly Style Perk.
Loot Pool
The loot pool of Arcane Anomalies is currently unknown.
Obtainment
Without any Style Perks, Arcane Anomalies have a 0% drop rate, increasing up to 0.1% drop chance whenever a daily or weekly quest is claimed, the Daily Meter or the Weekly Vault. The number of reward crates from each claim doesn't affect the chances of an Arcane Anomaly drop.