Drop Mechanics

Step One: Gold

After defeating a monster or opening a chest, each player receives loot. A number of rolls are made to determine exactly what loot they find. When a chest is opened, or after successfully completing a combat encounter, each player makes a 1d100 Loot Roll. A player's Fortune Modifiers granted by items like the Gold Pouch are added to their loot roll. This sum is known as a Fortune Roll. The amount of gold each player finds is equal to their Fortune Roll multiplied by the Summative Battle CR, so for monster drops (Fortune Roll * ΣCR = Gold). For chests, the multiplier is at the DM’s discretion, but cases where a chest is located in a lethal area may warrant a higher multiplier.
If any player's Fortune Roll is 90+, they double the multiplier for all players, and the low-roll threshold is 25 (any player who rolled <25 on their loot roll may treat their roll as a 25).
If any player's Fortune Roll is 95+, they quadruple the multiplier for all players and the low-roll threshold is 50.
If any player's Loot Roll is 100, they 10x the multiplier for all players and the low-roll threshold is 75.
These multipliers stack!

Step Two: The Drop

Once the gold is calculated, the DM adds the players fortune rolls (disregarding low-roll thresholds) and divides by the number of players, generating the average. This number is added to the Summative Battle CR of the combat encounter (Fortune Roll Avg + CR = Tier) to determine the “drop tier” from which the players receive a reward. A random item is selected from this tier.
Note: although low thresholds are disregarded, loot roll modifiers from fortune items like the Gold Pouch are taken into consideration.
The player with the highest fortune roll receives the (first) drop. The received items can of course be traded or gifted to other party members. Ideally, players will see the value in equipping one another with strong gear.
The thresholds are as follows:

Average + CR	Drop Tier
0-50	Common
51-64	Uncommon
65-80	Rare
81-90	Very Rare
91-100	Legendary

The number of drops an encounter yields is dependent on the summative CR of the encounter.
The thresholds are as follows:

CR	# Drops
0-9	1
10-19	2
20-29	3
30-39	4
40-49	5

etc.
For encounters with multiple drops, the highest fortune roll receives the first drop. For all subsequent drops, the players who have not yet received a drop make another fortune roll. Like the first drop, the highest roller receives the drop and the drop tier is determined by the average of the players' fortune rolls added to the Summative Battle CR. Gold is only received on the fortune roll preceding the first drop.