Drelkor’s Compass is a random drop Unique item. You can do a few things to improve your odds of this item dropping:
- get the Grand Winds of Fortune blessing from the Fall of the Outcasts timeline, which grants “(16-22)% Increased Unique Drop Rate”.
- get the Grand Vigilance of the Damned blessing from the Blood, Frost, and Death timeline, which grants “(50-75)% Increased Bow Drop Rate”. These blessings result in more items of that type dropping while not reducing the drop rates of any other item types.
- farm the Fall of the Outcasts timeline whose exclusive echo rewards consist of Bows and Quivers. Increasing corruption and venturing further from the center of the timeline will increase the likelihood of these echoes spawning.
- build up corruption and enemy modifiers within timelines (preferably Empowered Timelines) to increase the “increased item rarity” stat. This modifier increases the average number of affixes on items, resulting in more Rare and Exalted items. It also increases the chance of finding Unique and Set items.
- lastly, you can use the Rune of Ascendance on any bow base type (that isn’t already a Unique/Set item) for a chance to roll any random drop Unique or Set item of that type. However, the chances for each amount of legendary potential are scaled as if the Unique had dropped at level 100, but are then reduced multiplicatively by a fixed value. Also, this is the most expensive option here as these runes are quite rare.
Doing all of these will maximize your odds of finding this item, and you have the highest chance of getting legendary potential on Uniques that drop in level 100 zones. Also, that item has an “Effective Level for Legendary Potential of 64”, which is a number used internally to calculate an items overall chance of rolling legendary potential with the higher the number equaling a lower chance of legendary potential rolling on the item.