If you are level 15, and you kill a level 9 legendary ghoul roamer, it will never spawn a flamer (level requirement 15) because the ghoul is too low level. Survival (the new survival, not launch survival): 1.5 There are a lot of numbers floating around on the internet for these modifiers, but the settings in the game files are as follows.

When an encounter is generated, your base legendary spawn chance (based on player level) is multiplied by a fixed number directly associated with the difficulty you are playing on. Game difficulty is another modifier in legendary enemy spawn chance. Over level 50 -> base 20% chance of legendary enemy spawning Less than or equal to level 50 -> base 18% chance of legendary enemy spawning Less than or equal to level 40 -> base 15% chance of legendary enemy spawning Less than or equal to level 30 -> base 12% chance of legendary enemy spawning Less than or equal to level 20 -> base 10% chance of legendary enemy spawning Less than or equal to level 5 -> no legendary enemies will spawn (except scripted events) There are a series of thresholds for legendary enemy spawn chances. Legendary enemies spawn based on a set of conditions The most efficient legendary farming method I discovered so far without the need to cheat console command, skip in game days or save scum.

Fallout 3 difficulty xp