I saw int he wiki that you can create an effect, that lets enemies drop items (like what Life Harvester does) but could you also make it that the an enemy itself would drop an item without having the need of owning a specific item/upgrade?
Or, in other words, that the enemy has this effect on all runs you do?
You could do it via a bullet pattern fairly easily using death_spiral_movement_driving_bullet_pattern, and then spawn entity.
Or
you could instead grant the enemy a single use system that drops (an) item(s).
Or
you can make it turn into an item on death.
most of the loot system is based on loot pools, which items are in which pools is a property of the item.
You can either make them drop something from a pool, or a specific item.
Making them drop sometimes is more difficult. Chance based things must be a effect (which normally means a system), or a modifier (what those can do is more limited, and is how the 5% chance of grants health on kill stuff works).