Random
Random assigns everyone a random role on startup. You never know what you'll get, leading to unique role combinations every game.
There are some restrictions during role assignment to try to guarantee proportioned village / wolf teams. The logic is inadequate, which often leads to games ending the first day or night. The logic also doesn't account for neutral roles, so this often leads to games with very few or no village-team roles.
The setting that controls role reveal on death is also randomized. In 1/3 of games, role reveal is on, in 1/3, it only reveals the team, and in 1/3 role reveal is off. If role reveal is off, then !stats also hides roles. Otherwise, it will choose 50/50 between hiding roles and only showing teams.
This mode changes totem odds, so that any kind of shaman can get any totem. The actual rates vary by totem, with some being up to 8x more likely than others to appear. For example, Death is the most common totem for shamans, with Impatience, Pacifism, and Influence following. Desperation and Luck are the most common for Wolf shaman.
Roles
First, it assigns a wolf role with kill powers to one player. Then, it creates a role pool containing all roles except for villager, cultist, thrall, and amnesiac. It starts assigning roles to players from the pool (the role isn't removed from the pool, so duplicates are possible). If the number of wolfteam + vampteam would total half of all players, it guarantees the next assignment won't be a wolfteam role or vampire.
After roles are assigned, it assigns a random percentage of players gunner roles. Gunners have a 2/3 change to be gunner and 1/3 change to be sharpshooter. It also assigns a random percentage of players to be assassin, guaranteeing at least 1. The amount of assassins will usually be around half the amount of gunners, but because of the multi-layered randomness in play it can vary. All roles can be assigned to be gunner or assassin, even if it's not normally allowed.